In these striking generalizations, which, though they contain a large amount of truth, are far from containing the whole truth, no room is left for the magnanimous parts of our nature to act; but the system of morals, prevailing at any one time or in any one class, is solely ascribed to the dictates of unalloyed selfishness. Adam Smith, by reasoning from this principle, with that exquisite subtlety which characterized his mind, explains many other circumstances which society presents, and which at first sight appear incongruous. According to the old notions, which, indeed, are not yet quite extinct, those who received wages were under a personal obligation to those who paid them; that is to say, they were under a moral obligation, over and above the obligation of performing certain services. It was believed that a master could not only select what servants he chose, but could pay them what he chose; or, at all events, that it was the will of the masters, considered as a body, which fixed the usual and average rate of wages.[682] The lower classes were, therefore, much indebted to the higher ones for giving them so much as they did; and it was incumbent upon all persons, who received wages, to take them with humble thankfulness, and with a feeling of gratitude, on account of the favour bestowed upon them by the generosity of their superiors.

This doctrine, so convenient to the upper classes of society, and so natural to the universal ignorance which formerly prevailed on these matters, began to be shaken by the speculative thinkers of the seventeenth century; but it was reserved for the eighteenth century to overthrow it, by letting in the great idea of necessity, and proving, that the rate of wages established in a country, was the inevitable consequence of the circumstances in which that country was placed, and had no connexion with the wishes of any individual, or, indeed, with the wishes of any class. To all instructed persons, this is now a familiar truth. Its discovery has excluded the notion of gratitude from the pecuniary relation between employers and employed, and has made known that servants or workmen who receive wages, have no more reason to be grateful than those who pay them. For, no choice having been exercised in fixing the wages, no favour can be conferred in their payment. The whole process is compulsory, and is the result of what had previously happened. Scarcely had the eighteenth century passed away, when this most important discovery was completed. It was decisively proved, that the reward of labour depends solely on two things; namely, the magnitude of that national fund out of which all labour is paid, and the number of the labourers among whom the fund is to be divided.

This vast step in our knowledge is due, mainly, though not entirely, to Malthus, whose work on Population, besides marking an epoch in the history of speculative thought, has already produced considerable practical results, and will probably give rise to others more considerable still. It was published in 1798; so that Adam Smith, who died in 1790, missed what to him would have been the intense pleasure of seeing how, in it, his own views were expanded rather than corrected. Indeed, it is certain, that without Smith there would have been no Malthus; that is, unless Smith had laid the foundation, Malthus could not have raised the superstructure. It was Adam Smith, who, far more than any other man, introduced the conception of uniform and necessary sequence into the apparently capricious phenomena of wealth, and who studied those phenomena by the aid of principles, of which selfishness alone supplied the data. According to his view, the employers of labour have, as employers, no benevolence, no sympathy, no virtue of any kind. Their sole aim is, their own selfish interest. They are constantly engaged in a tacit, if not in an open, combination, to prevent the lower ranks from being benefited by a rise of wages; and they sometimes combine for the purpose even of depressing those wages below their actual rate.[683] Having no bowels, they think only of themselves. The idea of their wishing to mitigate the inequalities of fortune, is to be exploded as one of the chimeras of that protective spirit, which imagined that society could not go on, unless the richer classes relieved the poorer ones, and sympathized with their troubles. This antiquated notion is further rebutted by the fact, that wages are always higher in summer than in winter, although the expenses which a labourer incurs in winter, being heavier than in summer, he ought, on principles of common humanity, to receive more money during the more expensive season.[684] In the same way, in years of scarcity, the dearness of food causes many persons to go to service, in order to support their families. The masters, instead of charitably paying such servants more on account of the unfortunate position in which they are placed, avail themselves of that position to pay them less. They make better terms for themselves; they lower wages just at the moment when sympathy for misfortune would have raised them; and, as they find that their servants, besides being worse remunerated, are, by poverty, made more submissive, they consider that scarcity is a blessing, and that dear years are to be commended as more favourable to industry than cheap ones.[685]

Adam Smith, therefore, though he failed in grasping the remote cause of the rate of wages, clearly saw that the approximate cause was, not the generosity of human nature, but its selfishness, and that the question was one of supply and demand; each side striving to extract as much as possible from the other.[686] By the aid of the same principle, he explained another curious fact, namely, the extravagant rewards bestowed on some of the most despicable classes of society, such, for instance, as opera-dancers, who always receive enormous pay for insignificant services. He observes, that one of the reasons why we pay them so highly, is, because we despise them. If to be a public dancer were a creditable occupation, more persons would be brought up to it, and the supply of public dancers becoming greater, competition would lower their wages. As it is, we look on them disdainfully. By way of compensating the disdain, we have to bribe them largely to induce them to follow their pursuit.[687] Here we see, that the reward which one class bestows on another, instead of being increased by sympathy, is increased by scorn; so that the more we contemn the tastes and the way of life of our fellow-creatures, the more liberal we are in recompensing them.

Passing to another, and somewhat different, class, Adam Smith threw new light on the cause of that hospitality for which the clergy were famous during the Middle Ages, and for the magnificence of which they have received great praise. He shows that, although they undoubtedly relieved a large amount of distress, this is not to be ascribed to them as a merit, since it resulted from the peculiarity of their position, and since, moreover, they did it for their own advantage. In the Middle Ages, the clergy possessed enormous wealth, and their revenues were mostly paid, not in money, but in kind, such as corn, wine, and cattle. Trade and manufactures being hardly known, the clergy could find no use for these commodities except to feed other people. By employing them in that way, they benefited themselves in the most effectual manner. They gained a reputation for extensive charity; they increased their influence; they multiplied the number of their adherents; and they not only advanced themselves to temporal power, but they secured to their spiritual threats a respect, which, without this contrivance, it would have been impossible for them to obtain.[688]

The reader will now be able to understand the nature of that method of investigation which is adopted in the Wealth of Nations, and of which I have given more instances than I should otherwise have done, partly because the question of philosophic method lies at the very root of our knowledge, and partly because no attempt has hitherto been made to analyze the intellect of Adam Smith, by considering his two great works as the opposite, but yet the compensatory, parts of a single scheme. And, as he is by far the greatest thinker Scotland has produced, I need hardly apologize, in a history of the Scotch mind, for devoting so much attention to his system, and endeavouring to examine it at its base. But, having done so, it would be a needless prolixity to treat with equal fulness the productions of those other eminent Scotchmen who lived at the same time, and nearly all of whom pursued a method essentially, though not entirely, the same; that is to say, they preferred the deductive process of reasoning from principles, to the inductive process of reasoning to them. In that peculiar form of deduction which consists in a deliberate suppression of part of the principles, Adam Smith stands alone. For, though others attempted to follow that plan, they did so irregularly, and at intervals, and did not, like him, see the importance of keeping close to their method, and of invariably abstaining from letting into the premisses of their arguments, considerations which would complicate the problem that they wished to solve.

Among the contemporaries of Adam Smith, one of the first, in eminence, as well as in reputation, is David Hume. His views respecting political economy were published in 1752,[689] that is, the very year in which Adam Smith taught the principles subsequently unfolded in the Wealth of Nations. But Hume, though a most accomplished reasoner, as well as a profound and fearless thinker, had not the comprehensiveness of Adam Smith, nor had he that invaluable quality of imagination without which no one can so transport himself into past ages as to realize the long and progressive movements of society, always fluctuating, yet, on the whole, steadily advancing. How unimaginative he was, appears, not only from the sentiments he expressed, but likewise from many traits in his private life.[690] It appears, also, in the very colour and mechanism of his language; that beautiful and chiselled style in which he habitually wrote, polished as marble, but cold as marble too, and wanting that fiery enthusiasm and those bursts of tempestuous eloquence, which, ever and anon, great objects naturally inspire, and which rouse men to their inmost depths. This it was, which, in his History of England,—that exquisite production of art, which, in spite of its errors, will be admired as long as taste remains among us,—prevented him from sympathizing with those bold and generous natures, who, in the seventeenth century, risked their all to preserve the liberty of their country. His imagination was not strong enough to picture the whole of that great century, with its vast discoveries, its longings after the unknown, its splendid literature, and what was better than all these, its stern determination to vindicate freedom, and to put down tyranny. His clear and powerful understanding saw these things separately, and in their various parts, but could not fuse them into a single form, because he lacked that peculiar faculty which assimilates the past to the present, and enables the mind to discern both with almost equal ease. That Great Rebellion, which he ascribed to the spirit of faction, and the leaders of which he turned into ridicule, was but the continuation of a movement which can be clearly traced to the twelfth century, and of which such events as the invention of printing, and the establishment of the Reformation, were merely successive symptoms. For all this, Hume cared nothing. In regard to philosophy, and in regard to the purely speculative parts of religious doctrines, his penetrating genius enabled him to perceive that nothing could be done, except by a spirit of fearless and unrestrained liberty. But this was the liberty of his own class; the liberty of thinkers, and not of actors. His absence of imagination prevented him from extending the range of his sympathy beyond the intellectual classes, that is, beyond the classes of whose feelings he was directly cognizant. It would, therefore, appear, that his political errors were due, not, as is commonly said, to his want of research, but rather to the coldness of his temperament.[691] It was this which made him stop where he did, and which gave to his works the singular appearance of a profound and original thinker, in the middle of the eighteenth century, advocating practical doctrines, so illiberal, that, if enforced, they would lead to despotism, and yet, at the same time, advocating speculative doctrines, so fearless and enlightened, that they were not only far in advance of his own age, but have, in some degree, outstripped even the age in which we live.

Among his speculative views, the most important are his theory of causation as discarding the idea of power, and his theory of the laws of association. Neither of these theories are, in their primary conception, quite original, but his treatment made them as valuable as if they had been entirely his own. His theory of miracles, in connexion, on the one hand, with the principles of evidence, and, on the other hand, with the laws of causation, is worked out with consummate skill, and, after having received the modifications subsequently imposed by Brown, has now become the foundation on which the best inquirers into these matters take their stand.[692] His work on the principles of morals, by generalizing the laws of expediency, prepared the way for Bentham, who afterwards incorporated with them an estimate of the more remote consequences of human actions; Hume, having chiefly confined himself to their more immediate consequences. The doctrine of utility was common to each; but while Hume applied it mainly to the individual, Bentham applied it to the surrounding society. Though Bentham was more comprehensive, yet Hume, having come first, was more original. The praise of originality must also be accorded to his economical theories, in which he advocated those principles of free trade, which politicians began to adopt many years after his death.[693] In opposition to the notions then prevailing, he distinctly asserted, that all commodities, though apparently bought by money, are in reality bought by labour.[694] Money, therefore, is not the subject of commerce, and is of no use except to facilitate it.[695] Hence, it is absurd for a nation to trouble itself about the balance of trade, or to make regulations to discourage the exportation of the precious metals.[696] Neither does the average rate of interest depend on their scarcity or abundance, but upon the operation of more general causes.[697] As a necessary consequence of these positions, Hume inferred that the established policy was wrong, which made trading states look upon each other as rivals, while, in point of fact, the question, if considered from a certain height, was one, not of rivalry, but of coöperation; every country being benefited by the increasing wealth of its neighbours.[698] Those who know the character of commercial legislation, and the opinions of even the most enlightened statesmen a century ago, will consider these views as extremely remarkable to have been propounded in the year 1752. But what is more remarkable still, is, that their author subsequently detected the fundamental error which Adam Smith committed, and which vitiates many of his conclusions. The error consists in his having resolved price into three components, namely, wages, profit, and rent; whereas it is now known that price is a compound of wages and profit, and that rent is not an element of it, but a result of it. This discovery is the corner-stone of political economy; but it is established by an argument so long and so refined, that most minds are unable to pursue it without stumbling, and the majority of those who acquiesce in it are influenced by the great writers to whom they pay deference, and whose judgment they follow. It is, therefore, a striking proof of the sagacity of Hume, that in an age when the science was but dawning, and when he could receive little help from his predecessors, he should have discovered a mistake of this sort, which lies so far beneath the surface. Directly the Wealth of Nations appeared, he wrote to Adam Smith, disputing his position that rent is a part of price;[699] and this letter, written in the year 1776, is the first indication of that celebrated theory of rent, which, a little later, Anderson, Malthus, and West, saw, and imperfectly developed, but which it was reserved for the genius of Ricardo to build up on a broad and solid foundation.

It is very observable, that Hume and Adam Smith, who made such immense additions to our knowledge of the principles of trade, had no practical acquaintance with it.[700] Hume had, at an early period of his life, been in a mercantile house; but he threw up that employment in disgust, and buried himself in a provincial town, to think, rather than to observe.[701] Indeed, one of the capital defects of his mind, was a disregard of facts. This did not proceed, as is too often the case, from that worst form of moral obliquity, an indifference to truth; since he, on the contrary, was an ardent lover of it, and was, moreover, a man of the purest and most exemplary character, utterly incapable of falsehood, or of prevarication of any kind.[702] In him, a contempt for facts was merely the exaggerated result of a devotion to ideas. He not only believed, with perfect justice, that ideas are more important than facts, but he supposed that they should hold the first place in the order of study, and that they should be developed before the facts are investigated. The Baconian philosophy, which, though it allows a preliminary and tentative hypothesis, strongly insists upon the necessity of first collecting the facts, and then proceeding to the ideas, excited his aversion; and this, I have no doubt, is the reason why he, who was usually so lenient in his judgments, and was so keen an admirer of intellectual greatness is, nevertheless, grossly unfair towards Bacon, with whose method it was impossible for him to sympathize, though he could not deny its utility, in physical science.[703] If Hume had followed the Baconian scheme, of always rising from particulars to generals, and from each generalization to that immediately above it, he would hardly have written one of his works. Certainly, his economical views would never have appeared, since political economy is as essentially a deductive science as geometry itself.[704] Reversing the inductive process, he was in favour of beginning with what he termed general arguments, by which he hoped to demonstrate the inaccuracy of opinions which facts were supposed to have proved.[705] He did not stop to investigate the facts from which the inference had been drawn, but he inverted the order by which the inference was to be obtained. The same dislike to make the facts of trade the basis of the science of trade, was displayed by Adam Smith, who expresses his want of confidence in statistics, or, as it was then termed, political arithmetic.[706] It is, however, evident, that statistical facts are as good as any other facts, and, owing to their mathematical form, are very precise.[707] But when they concern human actions, they are the result of all the motives which govern those actions; in other words, they are the result, not merely of selfishness, but also of sympathy. And as Adam Smith, in the Wealth of Nations, dealt with only one of these passions, namely, selfishness, he would have found it impossible to conduct his generalization from statistics, which are necessarily collected from the products of both passions. Such statistical facts were, in their origin, too complex to be generalized; especially as they could not be experimented upon, but could only be observed and arranged. Adam Smith, perceiving them to be unmanageable, very properly rejected them as the basis of his science, and merely used them by way of illustration, when he could select what he liked. The same remark applies to other facts which he drew from the history of trade, and, indeed, from the general history of society. All of these are essentially subsequent to the argument. They make the argument more clear, but not more certain. For, it is no exaggeration to say, that, if all the commercial and historical facts in the Wealth of Nations were false, the book would still remain, and its conclusions would hold equally good, though they would be less attractive. In it, every thing depends upon general principles, and they, as we have seen, were arrived at in 1752, that is, twenty-four years before the work was published in which those principles were applied. They must, therefore, have been acquired independently of the facts which Adam Smith, subsequently incorporated with them, and which he learnt during that long period of twenty-four years. And the ten years which he employed in composing his great work, were not spent in one of those busy haunts of men, where he might have observed all the phenomena of industry, and studied the way in which the operations of trade affect human character, and are affected by it. He did not resort to one of those vast marts and emporiums of commerce, where the events were happening which he was seeking to explain. That was not his method. On the contrary, the ten years, during which he was occupied in raising to a science the most active department of life, were passed in complete seclusion in Kirkaldy, his quiet little birthplace.[708] He had always been remarkable for absence of mind, and was so little given to observation, as to be frequently oblivious of what was passing around him.[709] In that obliviousness, he, amid the tranquil scenes of his childhood, could now indulge without danger. There, cheered, indeed, by the society of his mother, but with no opportunity of observing human nature upon a large scale, and far removed from the hum of great cities, did this mighty thinker, by the force of his own mind, unravel the numerous and complicated phenomena of wealth, detect the motives which regulate the conduct of the most energetic and industrious portion of mankind, and lay bare the schemes and the secrets of that active life from which he was shut out, while he, immured in comparative solitude, was unable to witness the very facts which he succeeded in explaining.

The same determination to make the study of principles precede that of facts, is exhibited by Hume in one of his most original works, the Natural History of Religion. In reference to the title of this treatise, we must observe that, according to the Scotch philosophers, the natural course of any movement is by no means the same as its actual course. This discrepancy between the ideal and the real, was the unavoidable result of their method.[710] For, as they argued deductively from fixed premisses, they could not take into account the perturbations to which their conclusions were liable, from the play and friction of the surrounding society. To do that, required a separate inquiry. It would have been needful to investigate the circumstances which caused the friction, and thus prevented the conclusions from being, in the world of fact, the same as they were in the world of speculation. What we call accidents, are constantly happening, and they prevent the real march of affairs from being identical with the natural march. And, as long as we are unable to predict those accidents, there will always be a want of complete harmony between the inferences of a deductive science and the realities of life; in other words, our inferences will tend towards truth, but never completely attain it.[711]

With peculiar propriety, therefore, did Hume term his work a Natural History of Religion. It is an admirable specimen of the deductive method. Its only fault is that he speaks too confidently of the accuracy of the results to which, on such a subject, that method could attain. He believed, that, by observing the principles of human nature, as he found them in his own mind, it was possible to explain the whole course of affairs, both moral and physical.[712] These principles were to be arrived at by experiments made on himself; and having thus arrived at them, he was to reason from them deductively, and so construct the entire scheme. This he contrasts with the inductive plan, which he calls a tedious and lingering process; and while others might follow that slow and patient method of gradually working their way towards first principles, his project was, to seize them at once, or, as he expresses himself, not to stop at the frontier, but to march directly on the capital, being possessed of which, he could gain an easy victory over other difficulties, and could extend his conquests over the sciences.[713] According to Hume, we are to reason, not in order to obtain ideas, but we are to have clear ideas before we reason.[714] By this means, we arrive at philosophy; and her conclusions are not to be impugned, even if they do happen to clash with science. On the contrary, her authority is supreme, and her decisions, being essentially true, must always be preferred to any generalization of the facts which the external world presents.[715]

Hume, therefore, believed that all the secrets of the external world are wrapped up in the human mind. The mind was not only the key by which the treasure could be unlocked; it was also the treasure itself. Learning and science might illustrate and beautify our mental acquisitions, but they could not communicate real knowledge; they could neither give the prime original materials, nor could they teach the design according to which those materials must be worked.

In conformity with these views, the Natural History of Religion was composed. The object of Hume in writing it, was, to ascertain the origin and progress of religious ideas; and he arrives at the conclusion, that the worship of many Gods must, every where, have preceded the worship of one God. This, he regards as a law of the human mind, a thing not only that always has happened, but that always must happen. His proof is entirely speculative. He argues that the earliest state of man is necessarily a savage state; that savages can feel no interest in the ordinary operations of nature, and no desire to study the principles which govern those operations; that such men must be devoid of curiosity on all subjects which do not personally trouble them; and that, therefore, while they neglect the usual events of nature, they will turn their minds to the unusual ones.[716] A violent tempest, a monstrous birth, excessive cold, excessive rain, sudden and fatal diseases, are the sort of things to which the attention of the savage is confined, and of which alone he desires to know the causes. Directly he finds that such causes are beyond his control, he reckons them superior to himself, and, being incapable of abstracting them, he personifies them; he turns them into deities; polytheism is established; and the earliest creed of mankind assumes a form which can never be altered, as long as men remain in this condition of pristine ignorance.[717]

These propositions, which are not only plausible, but which are probably true, ought, according to the inductive philosophy, to have been generalized from a survey of facts; that is, from a collection of evidence respecting the state of religion and of the speculative faculties among savage tribes. But this, Hume abstains from doing. He refers to none of the numerous travellers who have visited such people; he does not, in the whole course of his work, mention even a single book where facts respecting savage life are preserved. It was enough for him, that the progress from a belief in many Gods to a belief in one God, was the natural progress; which is saying, in other words, that it appeared to his mind to be the natural progress.[718] With that, he was satisfied. In other parts of his essay, where he treats of the religious opinions of the ancient Greeks and Romans, he displays a tolerable, though by no means remarkable, learning; but the passages which he cites, do not refer to that entirely barbarous society in which, as he supposes, polytheism first arose. The premisses, therefore, of the argument are evolved out of his own mind. He reasons deductively from the ideas which his powerful intellect supplied, instead of reasoning inductively from the facts which were peculiar to the subject he was investigating.

Even in the rest of his work, which is full of refined and curious speculation, he uses facts, not to demonstrate his conclusions, but to illustrate them. He, therefore, selected those facts which suited his purpose, leaving the others untouched. And this, which many critics would call unfair, was not unfair in him; because he believed, that he had already established his principles without the aid of those facts. The facts might benefit the reader, by making the argument clearer, but they could not strengthen the argument. They were more intended to persuade than to prove; they were rather rhetorical than logical. Hence, a critic would waste his time if he were to sift them with a minuteness which would be necessary, supposing that Hume had built an inductive argument upon them. Otherwise, without going far, it might be curious to contrast them with the entirely different facts which Cudworth, eighty years before, had collected from the same source, and on the same subject. Cudworth, who was much superior to Hume in learning, and much inferior to him in genius,[719] displayed, in his great work on the Intellectual System of the Universe, a prodigious erudition, to prove that, in the ancient world, the belief in one God was a prevailing doctrine. Hume, who never refers to Cudworth, arrives at a precisely opposite conclusion. Both quoted ancient writers; but while Cudworth drew his inferences from what he found in those writers, Hume drew his from what he found in his own mind. Cudworth, being more learned, relied on his reading; Hume, having more genius, relied on his intellect. Cudworth, trained in the school of Bacon, first collected the evidence, and then passed the judgment. Hume, formed in a school entirely different, believed that the acuteness of the judge was more important than the quantity of the evidence; that witnesses were likely to prevaricate; and that he possessed, in his own mind, the surest materials for arriving at an accurate conclusion. It is not, therefore, strange, that Cudworth and Hume, pursuing opposite methods, should have obtained opposite results, since such a discrepancy is, as I have already pointed out, unavoidable, when men investigate, according to different plans, a subject which, in the existing state of knowledge, is not amenable to scientific treatment.

The length to which this chapter has already extended, and the number of topics which I have still to handle, will prevent me from examining, in detail, the philosophy of Reid, who was the most eminent among the purely speculative thinkers of Scotland, after Hume and Adam Smith, though, in point of merit, he must be placed far below them. For, he had neither the comprehensiveness of Smith, nor the fearlessness of Hume. The range of his knowledge was not wide enough to allow him to be comprehensive; while a timidity, almost amounting to moral cowardice, made him recoil from the views advocated by Hume, not so much on account of their being false, as on account of their being dangerous. It is, however, certain, that no man can take high rank as a philosopher, who allows himself to be trammelled by considerations of that kind. A philosopher should aim solely at truth, and should refuse to estimate the practical tendency of his speculations. If they are true, let them stand; if they are false, let them fall. But, whether they are agreeable or disagreeable, whether they are consolatory or disheartening, whether they are safe or mischievous, is a question, not for philosophers, but for practical men. Every new truth which has ever been propounded, has, for a time, caused mischief; it has produced discomfort, and often unhappiness, sometimes by disturbing social or religious arrangements, and sometimes merely by the disruption of old and cherished associations of thought. It is only after a certain interval, and when the framework of affairs has adjusted itself to the new truth, that its good effects preponderate; and the preponderance continues to increase, until, at length, the truth causes nothing but good. But, at the outset, there is always harm. And, if the truth is very great, as well as very new, the harm is serious. Men are made uneasy; they flinch; they cannot bear the sudden light; a general restlessness supervenes; the face of society is disturbed, or perhaps convulsed; old interests, and old beliefs, are destroyed, before new ones have been created. These symptoms are the precursors of revolution; they have preceded all the great changes through which the world has passed; and while, if they are not excessive, they forebode progress, so if they are excessive, they threaten anarchy. It is the business of practical men to moderate such symptoms, and to take care that the truths which philosophers discover, are not applied so rashly as to dislocate the fabric, instead of strengthening it. But the philosopher has only to discover the truth, and promulgate it; and that is hard work enough for any man, let his ability be as great as it may. This division of labour, between thinkers and actors, secures an economy of force, and prevents either class from wasting its power. It establishes a difference between science, which ascertains principles, and art, which applies them. It also recognizes, that the philosopher and the practical man, having each a separate part to play, each is, in his own field, supreme. But it is a sad confusion for either to interfere with the other. In their different spheres, both are independent, and both are worthy of admiration. Inasmuch, however, as practical men should never allow the speculative conclusions of philosophers, whatever be their truth, to be put in actual operation, unless society is, in some degree, ripe for their reception; so, on the other hand, philosophers are not to hesitate, and tremble, and stop short in their career, because their intellect is leading them to conclusions subversive of existing interests. The duty of a philosopher is clear. His path lies straight before him. He must take every pains to ascertain the truth; and, having arrived at a conclusion, he, instead of shrinking from it because it is unpalatable, or because it seems dangerous, should on that very account, cling the closer to it, should uphold it in bad repute, more zealously than he would have done in good repute; should noise it abroad far and wide, utterly regardless what opinions he shocks, or what interests he imperils; should, on its behalf, court hostility and despise contempt, being well assured, that, if it is not true, it will die, but that, if it is true, it must produce ultimate benefit, albeit unsuited for practical adoption by the age or country in which it is first propounded.

But Reid, notwithstanding the clearness of his mind and his great powers of argument, had so little of the real philosophic spirit, that he loved truth, not for its own sake, but for the sake of its immediate and practical results. He himself tells us, that he began to study philosophy, merely because he was shocked at the consequences at which philosophers had arrived. As long as the speculations of Locke and of Berkeley were not pushed to their logical conclusions, Reid acquiesced in them, and they were good in his eyes.[720] While they were safe and tolerably orthodox, he was not over-nice in inquiring into their validity. In the hands of Hume, however, philosophy became bolder and more inquisitive; she disturbed opinions which were ancient, and which it was pleasant to hold; she searched into the foundation of things, and by forcing men to doubt and to inquire, she rendered inestimable service to the cause of truth. But this was precisely the tendency at which Reid was displeased. He saw that such disturbance was uncomfortable; he saw that it was hazardous; therefore, he endeavoured to prove that it was groundless. Confusing the question of practical consequences with the totally different question of scientific truth, he took for granted that, because to his age the adoption of those consequences would be mischievous, they must be false. To the profound views of Hume respecting causation, he gravely objects, that if they were carried into effect, the operation of criminal law would be imperilled.[721] To the speculations of the same philosopher concerning the metaphysical basis of the theory of contracts, he replies, that such speculations perplex men, and weaken their sense of duty; they are, therefore, to be disapproved of, on account of their tendency.[722] With Reid, the main question always is, not whether an inference is true, but what will happen if it is true. He says, that a doctrine is to be judged by its fruits;[723] forgetting that the same doctrine will bear different fruits in different ages, and that the consequences which a theory produces in one state of society, are often diametrically opposed to those which it produces in another. He thus made his own age the standard of all future ones. He also trammelled philosophy with practical considerations; diverting thinkers from the pursuit of truth, which is their proper department, into the pursuit of expediency, which is not their department at all. Reid was constantly stopping to inquire, not whether theories were accurate, but whether it was advisable to adopt them; whether they were favourable to patriotism, or to generosity, or to friendship;[724] in a word, whether they were comfortable, and such as we should at present like to believe.[725] Or else, he would take other ground, still lower, and still more unworthy of a philosopher. In opposing, for instance, the doctrine, that our faculties sometimes deceive us,—a doctrine which, as he well knew, had been held by men whose honesty was equal to his own, and whose ability was superior to his own,—he does not scruple to enlist on his side the prejudices of a vulgar superstition; seeking to blacken the tenet which he was unable to refute. He actually asserts, that they who advocate it, insult the Deity, by imputing to the Almighty that He has lied. Such being the consequence of the opinion, it of course follows that the opinion must be rejected without further scrutiny, since, to accept it, would produce fatal results on our conduct, and would, indeed, be subversive of all religion, of all morals, and of all knowledge.[726]

In 1764, Reid published his Inquiry into the Human Mind; and in that, and in his subsequent work, entitled Essays on the Powers of the Mind, he sought to destroy the philosophy of Locke, Berkeley, and Hume. And as Hume was the boldest of the three, it was chiefly his philosophy which Reid attacked. Of the character of this attack, some specimens have just been given; but they rather concern his object and motives, while what we have now to ascertain is, his method, that is, the tactics of his warfare. He clearly saw, that Hume had assumed certain principles, and had reasoned deductively from them to the facts, instead of reasoning inductively from the facts to them. To this method, he strongly, and perhaps fairly, objects. He admits that Hume had reasoned so accurately, that if his principles were conceded, his conclusions must likewise be conceded.[727] But, he says, Hume had no right to proceed in such a manner. He had no right to assume principles, and then to argue from them. The laws of nature were to be arrived at, not by conjecturing in this way, but by a patient induction of facts.[728] Discoveries depended solely on observation and experiment; and any other plan could only produce theories, ingenious, perhaps, and plausible, but quite worthless.[729] For, theory should yield to fact, and not fact to theory.[730] Speculators, indeed, might talk about first principles, and raise a system by reasoning from them. But, the fact was, that there was no agreement as to how a first principle was to be recognized; since a principle which one man would deem self-evident, another would think it necessary to prove, and a third would altogether deny.[731]

The difficulties of deductive reasoning are here admirably portrayed. It might have been expected, that Reid would have built up his own philosophy according to the inductive plan, and would have despised that assumption of first principles, with which he taunts his opponents. But it is one of the most curious things in the history of metaphysics, that Reid after impeaching the method of Hume, follows the very same method himself. When he is attacking the philosophy of Hume, he holds deduction to be wrong. When he is raising his own philosophy, he holds it to be right. He deemed certain conclusions dangerous, and he objects to their advocates, that they argued from principles, instead of from facts: and that they assumed themselves to be in possession of the first principles of truth, although people were not agreed as to what constituted a first principle. This is well put, and hard to answer. Strange, however, to say, Reid arrives at his own conclusions, by assuming first principles to an extent far greater than had been done by any writer on the opposite side. From them, he argues; his whole scheme is deductive; and his works scarcely contain a single instance of that inductive logic, which, when attacking his opponents, he found it convenient to recommend. It is difficult to conceive a better illustration of the peculiar character of the Scotch intellect in the eighteenth century, and of the firm hold, which, what may be called, the anti-Baconian method, had upon that intellect. Reid was a man of considerable ability, of immaculate honesty, and was deeply convinced that it was for the good of society that the prevailing philosophy should be overthrown. To the performance of that task, he dedicated his long and laborious life; he saw that the vulnerable point of the adverse system was its method; he indicated the deficiencies of that method, and declared, perhaps wrongly, but at all events sincerely, that it could never lead to truth. Yet, and notwithstanding all this, such was the pressure of the age in which he lived, and so completely did the force of circumstances shape his understanding, that, in his own works, he was unable to avoid that very method of investigation which he rebuked in others. Indeed, so far from avoiding it, he was a slave to it. The evidence of this I will now give, because, besides its importance for the history of the Scotch mind, it is valuable as one of many lessons, which teach us how we are moulded by the society which surrounds us; how even our most vigorous actions are influenced by general causes of which we are often ignorant, and which few of us care to study; and, finally, how lame and impotent we are, when, as individuals, we try to stem the onward current, resisting the great progress instead of aiding it, and vainly opposing our little wishes to that majestic course of events, which admits of no interruption, but sweeps on, grand and terrible, while generation after generation passes away, successively absorbed in one mighty vortex.

Directly Reid, ceasing to refute the philosophy of Hume, began to construct his own philosophy, he succumbed to the prevailing method. He now assures us, that all reasoning must be from first principles, and that, so far from reasoning to those principles, we must at once admit them, and make them the basis of all subsequent arguments.[732] Having admitted them, they become a thread to guide the inquirer through the labyrinth of thought.[733] His opponents had no right to assume them, but he might do so, because to him they were intuitive.[734] Whoever denied them, was not fit to be reasoned with.[735] Indeed, to investigate them, or to seek to analyze them, was wrong as well as foolish, because they were part of the constitution of things; and of the constitution of things no account could be given, except that such was the will of God.[736]

As Reid obtained his first principles with such ease, and as he carefully protected them by forbidding any attempt to resolve them into simpler elements, he was under a strong temptation to multiply them almost indefinitely, in order that, by reasoning from them, he might raise a complete and harmonious system of the human mind. To that temptation he yielded with a readiness, which is truly surprising, when we remember how he reproached his opponents with doing the same thing. Among the numerous first principles which he assumes, not only as unexplained, but as inexplicable, are the belief in Personal Identity;[737] the belief in the External World;[738] the belief in the Uniformity of Nature;[739] the belief in the Existence of Life in Others;[740] the belief in Testimony;[741] also in the power of distinguishing truth from error,[742] and even in the correspondence of the face and voice to the thoughts.[743] Of belief generally, he asserts that there are many principles,[744] and he regrets that any one should have rashly attempted to explain them.[745] Such things are mysterious, and not to be pried into. We have also other faculties, which being original and indecomposable, resist all inductive treatment, and can neither be resolved into simpler elements, nor referred to more general laws. To this class, Reid assigns Memory,[746] Perception,[747] Desire of Self-Approbation,[748] and not only Instinct, but even Habit.[749] Many of our ideas, such as those concerning Space and Time, are equally original;[750] and other first principles there are, which have not been enunciated, but from which we may reason.[751] They, therefore, are the major premisses of the argument; no reason having yet been given for them, they must be simple; and not having yet been explained, they are, of course, inexplicable.[752]

All this is arbitrary enough. Still, in justice to Reid, it must be said, that, having made these assumptions, he displayed remarkable ability in arguing from them, and that, in attacking the philosophy of his time, he subjected it to a criticism, which has been extremely serviceable. His lucidity, his dialectic skill, and the racy and masculine style in which he wrote, made him a formidable opponent, and secured to his objections a respectful hearing. To me, however, it appears, that notwithstanding the attempts, first of M. Cousin, and afterwards of Sir William Hamilton, to prop up his declining reputation, his philosophy, as an independent system, is untenable, and will not live. In this I may be mistaken; but what is quite certain is, that nothing can be more absurd than to suppose, as some have done, that he adopted the inductive, or, as it is popularly called, Baconian method. Bacon, indeed, would have smiled at such a disciple, assuming all sorts of major premisses, taking general principles for granted with the greatest recklessness, and reserving his skill for the task of reasoning from propositions for which he had no evidence, except that on a cursory, or, as he termed it, a common-sense, inspection, they appeared to be true.[753] This refusal to analyze preconceived notions, comes under the head of what Bacon stigmatized as the anticipatio naturæ, and which he deemed the great enemy of knowledge, on account of the dangerous confidence it places in the spontaneous and uncorrected conclusions of the human mind. When, therefore, we find Reid holding up the Baconian philosophy, as a pattern which it behoves all inquirers to follow;[754] and when we, moreover, find Dugald Stewart, who, though a somewhat superficial thinker, was, at all events, a careful writer, supposing that Reid had followed it,[755] we meet with fresh proof of how difficult it was for Scotchmen of the last age to imbibe the true spirit of inductive logic, since they believed, that a system which flagrantly violated its rules, had been framed in strict accordance with them.

Leaving mental philosophy, I now come to physical science, in which, if anywhere, we might expect that the inductive plan would predominate, and would triumph over the opposite, or deductive, one. How far this was the case, I will endeavour to ascertain, by an examination of the most important discoveries which have been made by Scotchmen concerning the organic and inorganic world. And, as my object is merely to indicate the turn and character of the Scotch mind, I shall avoid all details respecting the practical effects of those discoveries, and shall confine myself to such a narration as will exhibit their purely scientific aspect, so as to enable the reader to understand what additions were made to our knowledge of the laws of nature, and in what way the additions were made. The character of each discovery, and its process, will be stated, but nothing more. Neither here, nor in any part of this Introduction, do I pretend to investigate questions of practical utility, or to trace the connexion between the discoveries of science and the arts of life. That I shall do in the body of the work itself, where I hope to explain a number of minute social events, many of which are regarded as isolated, if not incongruous. For the present, I solely aim at those broad principles, which, by marking out the epochs of thought, underlie the whole fabric of society, and which must be clearly apprehended before history can cease to be a mere empirical assemblage of facts, of which the scientific basis being unsettled, the true order and coherence must be unknown.

Among the sciences which concern the inorganic world, the laws of heat occupy a conspicuous place. On the one hand, they are connected with geology, being intimately allied, and, indeed, necessarily bound up, with every speculation respecting the changes and present condition of the crust of the earth. On the other hand, they touch the great questions of life, both animal and vegetable; they have to do with the theory of species, and of race; they modify soil, food, and organization; and to them we must look for valuable help towards solving those great problems in biology, which, of late years, have occupied the attention of the boldest and most advanced philosophers.

Our present knowledge of the laws of heat, may be briefly stated as branching into five fundamental divisions. These are: latent heat; specific heat; the conduction of heat; the radiation of heat; and, finally, the undulatory theory of heat; by which last, we are gradually discarding our old material views, and are accustoming ourselves to look upon heat as simply one of the forms of force, all of which, such as light, electricity, magnetism, motion, gravitation, and chemical affinity, are constantly assuming each other's shape, but, in their total amount, are incapable either of increase or of diminution.[756] This grand conception, which is now placing the indestructibility of force on the same ground as the indestructibility of matter, has an importance far above its scientific value, considerable as that undoubtedly is. For, by teaching us, that nothing perishes, but that, on the contrary, the slightest movement of the smallest body, in the remotest region, produces results which are perpetual, which diffuse themselves through all space, and which, though they may be metamorphosed, cannot be destroyed, it impresses us with such an exalted idea of the regular and compulsory march of physical affairs, as must eventually influence other and higher departments of inquiry. Our habits of thought are so connected and interwoven, that notions of law and of the necessary concatenation of things, can never be introduced into one field of speculation, without affecting other fields which lie contiguous to it. When, therefore, the modern doctrine of conservation of force,[757] becomes firmly coupled with the older doctrine of conservation of matter, we may rest assured that the human mind will not stop there, but will extend to the study of Man, inferences analogous to those already admitted in the study of Nature. Having once recognized that the condition of the material universe, at any one moment, is simply the result of every thing which has happened at all preceding moments, and that the most trivial disturbance would so violate the general scheme, as to render anarchy inevitable, and that, to sever from the total mass even the minutest fragment, would, by dislocating the structure, bury the whole in one common ruin, we, thus admitting the exquisite adjustment of the different parts, and discerning, too, in the very beauty and completeness of the design, the best proof that it has never been tampered with by the Divine Architect, who called it into being, in whose Omniscience both the plan, and the issue of the plan, resided with such clearness and unerring certainty, that not a stone in that superb and symmetrical edifice has been touched since the foundation of the edifice was laid, are, by ascending to this pitch and elevation of thought, most assuredly advancing towards that far higher step, which it will remain for our posterity to take, and which will raise their view to so commanding a height, as to insure the utter rejection of those old and eminently irreligious dogmas of supernatural interference with the affairs of life, which superstition has invented, and ignorance has bequeathed, and the present acceptance of which betokens the yet early condition of our knowledge, the penury of our intellectual resources, and the inveteracy of the prejudices in which we are still immersed.

It is, therefore, natural, that the physical doctrine of indestructibility applied to force as well as to matter, should be essentially a creation of the present century, notwithstanding a few allusions made to it by some earlier thinkers, all of whom, however, groped vaguely, and without general purpose. No preceding age was bold enough to embrace so magnificent a view as a whole, nor had any preceding philosophers sufficient acquaintance with nature to enable them to defend such a conception, even had they desired to entertain it. Thus, in the case now before us, it is evident, that while heat was believed to be material, it could not be conceived as a force, and therefore no one could grasp the theory of its metamorphosis into other forces; though there are passages in Bacon which prove that he wished to identify it with motion. It was first necessary to abstract heat into a mere property or affection of matter, and there was no chance of doing this until heat was better understood in its immediate antecedents, that is, until, by the aid of mathematics, its proximate laws had been generalized. But, with the single exception of Newton, whose efforts, notwithstanding his gigantic powers, were, on this subject, very unsatisfactory, and who, moreover, had a decided leaning towards the material theory, no one attempted to unravel the mathematical laws of heat till the latter half of the eighteenth century, when Lambert and Black began the career which Prevost and Fourier followed up. The mind, having been so slow in mastering the preliminaries and outworks of the inquiry, was not ripe for the far more difficult enterprise of idealizing heat itself, and so abstracting it, as to strip it of its material attributes, and leave it to nothing but the speculative notion of an immaterial force.

From these considerations, which were necessary to enable the reader to appreciate the value of what was done in Scotland, it will be seen how essential it was that the laws of the movement of heat should be studied before its nature was investigated, and before the emission theory could be so seriously attacked as to allow of the possibility of that great doctrine of the indestructibility of force, which, I make no doubt, is destined to revolutionize our habits of thought, and to give to future speculations a basis infinitely wider than any previously known. In regard to the movements of heat, we owe the laws of conduction and of radiation chiefly to France and Geneva, while the laws of specific heat, and those of latent heat, were discovered in Scotland. The doctrine of specific heat, though interesting, has not the scientific importance which belongs to the other departments of this great subject; but the doctrine of latent heat is extremely curious, not only in itself, but also on account of the analogies it suggests with various branches of physical inquiry.

What is termed latent heat, is exhibited in the following manner. If, in consequence of the application of heat, a solid passes into a liquid, as ice, for instance, into water, the conversion occupies a longer time than could be explained by any theory which had been propounded down to the middle of the eighteenth century. Neither was it possible to explain how it is, that ice never rises above the temperature of 32° until it is actually melted, no matter what the heat of the adjacent bodies may be. There were no means of accounting for these circumstances. And though practical men, being familiar with them, did not wonder at them, they caused great astonishment among thinkers, who were accustomed to analyze events, and to seek a reason for common and every-day occurrences.

Soon after the middle of the eighteenth century, Black, who was then one of the professors in the University of Glasgow, turned his attention to this subject.[758] He struck out a theory which, being eminently original, was violently attacked, but is now generally admitted. With a boldness and reach of thought not often equalled, he arrived at the conclusion, that whenever a body loses some of its consistence, as in the case of ice becoming water, or water becoming steam, such body receives an amount of heat which our senses, though aided by the most delicate thermometer, can never detect. For, this heat is absorbed; we lose all sight of it, and it produces no palpable effect on the material world, but becomes, as it were, a hidden property. Black, therefore, called it latent heat, because, though we conceive it as an idea, we cannot trace it as a fact. The body is, properly speaking, hotter; and yet its temperature does not rise. Directly, however, the foregoing process is inverted, that is to say, directly the steam is condensed into water, or the water hardened into ice, the heat returns into the world of sense; it ceases to be latent, and communicates itself to the surrounding objects. No new heat has been created; it has, indeed, appeared and disappeared, so far as our senses are concerned; but our senses were deceived, since there has, in truth, been neither addition nor diminution.[759] That this remarkable theory paved the way for the doctrine of the indestructibility of force, will be obvious to whoever has examined the manner in which, in the history of the human mind, scientific conceptions are generated. The process is always so slow, that no single discovery has ever been made, except by the united labours of several successive generations. In estimating, therefore, what each man has done, we must judge him, not by the errors he commits, but by the truths he propounds. Most of his errors are not really his own. He inherits them from his predecessors; and if he throws some of them off, we should be grateful, instead of being dissatisfied that he has not rejected all. Black, no doubt, fell into the error of regarding heat as a material substance, which obeys the laws of chemical composition.[760] But this was merely an hypothesis, which was bequeathed to him, and with which the existing state of thought forced him to encumber his theory. He inherited the hypothesis, and could not get rid of his troublesome possession. The real service which he rendered is, that, in spite of that hypothesis, which clung to him to the last, he, far more than any of his contemporaries, contributed towards the great conception of idealizing heat, and thus enabled his successors to admit it into the class of immaterial and supersensual forces. Once admitted into that class, the list of forces became complete; and it was comparatively easy to apply to the whole body of force, the same notion of indestructibility, which had previously been applied to the whole body of matter. But it was hardly possible to effect this object, while heat stood, as it were, midway between force and matter, yielding opposite results to different senses; amenable to the touch, but invisible to the eye. What was wanting, was to remove it altogether out of the jurisdiction of the senses, and to admit that, though we experience its effects, we can only conceive its existence. Towards accomplishing this, Black took a prodigious stride. Unconscious, perhaps, of the remote tendency of his own labours, he undermined that doctrine of material heat, which he seemed to support. For, by his advocacy of latent heat, he taught that its movements constantly baffle, not only some of our senses, but all of them; and that, while our feelings make us believe that heat is lost, our intellect makes us believe that it is not lost. Here, we have apparent destructibility, and real indestructibility. To assert that a body received heat without its temperature rising, was to make the understanding correct the touch, and defy its dictates. It was a bold and beautiful paradox, which required courage as well as insight to broach, and the reception of which marks an epoch in the human mind, because it was an immense step towards idealizing matter into force. Some, indeed, have spoken of invisible matter; but that is a contradiction in terms, which will never be admitted, as long as the forms of speech remain unchanged. Nothing can be invisible, except force, mind, and the Supreme Cause of all. We must, therefore, ascribe to Black the signal merit that he first, in the study of heat, impeached the authority of the senses, and thereby laid the foundation of every thing which was afterwards done. Besides the relation which his discovery bears to the indestructibility of force, it is also connected with one of the most splendid achievements effected by this generation in inorganic physics; namely, the establishment of the identity of light and heat. To the senses, light and heat, though in some respects similar, are in most respects dissimilar. Light, for instance, affects the eye, and not the touch. Heat affects the touch, but, under ordinary circumstances, does not affect the eye. The capital difference, however, between them is, that heat, unlike light, possesses the property of temperature; and this property is so characteristic, that until our understandings are invigorated by science, we cannot conceive heat separated from temperature, but are compelled to confuse one with the other. Directly, however, men began to adopt the method followed by Black, and were resolved to consider heat as supersensual, they entered the road which led to the discovery of light and heat being merely different developments of the same force. Ignoring the effects of heat on themselves, or on any part of the creation, which was capable of feeling its temperature, and would therefore be deceived by it, nothing was left for them to do, but to study its effects on the inanimate world. Then, all was revealed. The career of discovery was fairly opened; and analogies between light and heat, which even the boldest imagination had hardly suspected, were placed beyond a doubt. To the reflection of heat, which had been formerly known, were now added the refraction of heat, its double refraction, its polarization, its depolarization, its circular polarization, the interference of its rays, and their retardation; while, what is more remarkable than all, the march of our knowledge on these points was so swift, that before the year 1836 had come to a close, the chain of evidence was completed by the empirical investigations of Forbes and Melloni, they themselves little witting that every thing which they accomplished was prepared before they were born, that they were but the servants and followers of him who indicated the path in which they trod, and that their experiments, ingenious as they were, and full of resource, were simply the direct practical consequence of one of those magnificent ideas which Scotland has thrown upon the world, and the memory of which is almost enough so to bribe the judgment, as to tempt us to forget, that, while the leading intellects of the nation were engaged in such lofty pursuits, the nation itself, untouched by them, passed them over with cold and contemptuous indifference, being steeped in that deadening superstition, which turns a deaf ear to every sort of reason, and will not hearken to the voice of the charmer, charm he never so wisely.