Darwin

I

Mere observation of the natural world, varied, fascinating, inexhaustible as it is, affords only the material for science. Observed facts must be built up, woven together, ordered, arranged, systematized into conclusions and theories by reflection and reason, if they are to have full bearing on life and the universe. Knowledge is the accumulation of facts. Wisdom is the establishment of relations. And just because the latter process is delicate and perilous, it is all the more delightful. The lofty scorn of the true philosopher for mere perception is well shown in Royer Collard’s remark: ‘There is nothing so despicable as a fact.’ Which does not prevent philosophers or any one else from making facts the essential basis of all discussion of relations. Darwin’s own comments on the general connection between the two are always interesting: ‘I have an old belief that a good observer really means a good theorist,’[432] and again: ‘About thirty years ago there was much talk that geologists ought only to observe and not theorize; and I well remember some one saying that at this rate a man might as well go into a gravel-pit and count the pebbles and describe the colors. How odd it is that any one should not see that all observation must be for or against some view if it is to be of any service.’[433]

It is supposed to be one of the chief functions of education to develop this faculty of relating facts to each other and to train and strengthen the reasoning powers. Darwin did not feel that education did much for him in this line, at any rate in the scientific directions which were of especial interest to him. He believed that his academic discipline was largely wasted. Making Latin verses did not appeal. More general lines of current information attracted him very little, and he seemed at times oddly ignorant of what the ordinary educated man is expected to know. Thus his son records that he once asked Hooker where ‘this place Wien is where they publish so many books.’[434] He read vastly in all that concerned his own work, but that very fact prevented his keeping up with daily interests that were remote from it. His own comment on his university experience is bitter: ‘During the three years which I spent at Cambridge my time was wasted, as far as the academical studies were concerned, as completely as at Edinburgh and at school.’[435] And he believed that he had learned everything that to him was worth learning pretty much by his own efforts: ‘I consider that all I have learnt of any value has been self-taught.’[436]

With this sort of discipline behind him, it is of great interest to examine his general attitude toward the connection of reasoning and fact. To some of us the controversy between induction and deduction has always seemed rather profitless. The Baconian insistence upon the absolute necessity of fact as the basis of all solid theory is of course indisputably just. But to talk of proceeding from abstract theory to the investigation of fact seems as barren as to wander aimlessly in unassorted realms of fact without the assistance of theory. It is comforting, therefore, to find so clear and systematic a thinker as Huxley unwilling to identify his processes with either complete induction or deduction: ‘Those who refuse to go beyond fact rarely get as far as fact; and any one who has studied the history of science knows that almost every great step therein has been made by the “anticipation of nature,” that is, by the invention of hypotheses which, though verifiable, often had very little foundation to start with; and not unfrequently, in spite of a long career of usefulness, turned out to be wholly erroneous in the long run.’[437]

Now Darwin obviously finds himself in precisely the uncertainty between inductive and deductive methods that Huxley here indicates. His instincts were naturally hostile to abstract theory, which used facts as playthings to substantiate soaring conjecture. He says in regard to one scientific author: ‘I am not convinced, partly I think owing to the deductive cast of much of his reasoning; and I know not why, but I never feel convinced by deduction, even in the case of H. Spencer’s writings.’[438] And he speaks even more specifically concerning Spencer himself: ‘I always feel a malicious pleasure when a priori conclusions are knocked on the head; and therefore I felt somewhat like a devil when I read your remarks on Herbert Spencer.’[439] Early and late he emphasized that ‘no one has a right to speculate without distinct facts.’[440] Yet at the same time he urges and reiterates that the mere collection of facts, without some basis of theory for guidance and elucidation, is foolish and profitless: ‘I am a firm believer that without speculation there is no good and original observation.’[441]

The truth is, the importance of imaginative power in the equipment of a great scientist is often underestimated. Exact and watchful vision is the first necessity; but it does not go far, or not farthest, except as it has behind it the thoughts that wander through eternity, the vast and questing genius that is perpetually on the lookout for causes and explanations and is eager to evolve theory from the sure and substantial but inanimate basis of fact. Even Thoreau almost deplores his intense preoccupation with the fascinating business of observing: ‘Man cannot afford to be a naturalist, to look at Nature directly, but only with the side of his eye. He must look through and beyond her. To look at her is fatal as to look at the head of Medusa. It turns the man of science to stone. I feel that I am dissipated by so many observations.... I have almost a slight, dry headache as the result of all this observing.’[442] Theory, speculation, must be perpetually checked and restrained by the precision of systematic logic, but the accurate eye and the careful finger need to be supplemented by the eternally active mind.

As to the activity of Darwin’s mind there can be no question whatever. He not only saw, but he thought incessantly. If you compare the Beagle Journal with the Journal of Thoreau, you see at once how much more quick and ready the English naturalist is with speculation and conjecture. The smallest fact is apt to set him off on a train of theory, where Thoreau simply records, or possibly compares, and passes on. How significant is the brief comment of Asa Gray, in regard to some botanical point which as a specialist in that line he should have been the first to develop: ‘That is real Darwin. I just wonder you and I never thought of it. But he did.’[443] And he not only thought himself, he had the rarer and more valuable faculty of making others think. His mind was so intense and so magnetic in its constant activity that all those who came into contact with it were impelled and fired to work double on speculation of their own. ‘You stimulate my mind,’ says Gray again, ‘far more than any one else, except, perhaps Hooker.’[444]

On this point of intellectual fertility, as on his other scientific qualifications, it is most interesting to hear Darwin himself. The mental activity was present early and late, and it does not appear that the exuberance of youth especially emphasized it or that it tended to increase with the later desire to develop and elaborate his special theories. He himself says in the Autobiographical sketch: ‘I am not conscious of any change in my mind during the last thirty years, excepting in one point: ... I think that I have become a little more skillful in guessing right explanations and in devising experimental tests; but this may probably be the result of mere practice, and of a larger store of knowledge.’[445]

The quick intelligence was always working, sometimes wearily, sometimes eagerly, but working, unless absolute physical prostration forbade. When he is too exhausted, he complains: ‘Facts compel me to conclude that my brain was never formed for much thinking.’[446] But if so, he certainly lived contrary to his nature. He tells us that he cannot resist forming hypotheses on every subject.[447] Sometimes he bewails the tendency, realizing its drawbacks and dangers. Sometimes he gives way to it, recognizing its charm: ‘It is delightful to have many points fermenting in one’s brain.’[448] Speculation is fascinating. Theory gives form and texture to the fleeting drift and confusion of fact. Yet even when one indulges with most enthusiasm, a touch of humor shows that the satisfaction must be tempered with a certain lack of entire confidence: ‘That is a splendid fact about the white moths; it warms one’s very blood to see a theory thus almost proved to be true.’[449]

For the wonder and the interest of Darwin is, that, with such an eager and perpetual bent toward theorizing, he could keep the bent so fully under control. As Karl Pearson puts it, generally: ‘Hundreds of men have allowed their imagination to solve the universe, but the men who have contributed to our real understanding of natural phenomena have been those who were unstinted in their application of criticism to the product of their imaginations.’[450] Surely no man applied such criticism more carefully, more conscientiously, more constantly than Darwin. He analyzes his own position and sees the dangers of it: ‘Living so solitary as I do, one gets to think in a silly manner of one’s own work.’[451] He sees constantly how theory interferes and warps the judgment: ‘I have not a doubt that before many months are over I shall be longing for the most dishonest species as being more honest than the honestest theories.’[452] The possibility of error haunts him, torments him, and he knows well how apt his own speculative disposition is to mislead: ‘What you hint at generally is very, very true: that my work will be grievously hypothetical, and large parts by no means worthy of being called induction, my commonest error being probably induction from too few facts.’[453] As a consequence he was ever on his guard against being led astray. The tempting little demon of hypothesis might be luring round the corner: ‘It is as difficult not to form some opinion as it is to form a correct judgment.’[454] But whatever opinion was formed must be corrected, must be adjusted, must be tested, by the cold and rigid measure of fact. As he says himself, ‘I have steadily endeavored to keep my mind free so as to give up any hypothesis, however much beloved (and I cannot resist forming one on every subject), as soon as the facts are shown to be opposed to it.’[455] And one who knew him well and had studied him carefully says the same thing with equal emphasis: ‘His long experience had given him a kind of instinctive insight into the method of attack of any biological problem, however unfamiliar to him, while he rigidly controlled the fertility of his mind in hypothetical explanations by the no less fertility of ingeniously devised experiment.’[456]

In regard to this matter of speculative freedom and the tendency to let imagination run wild, it is interesting to watch Darwin’s comments on the general methods of others. The excess of abstinence he indeed deplores, recognizing that a man’s extreme caution may prevent him from theorizing enough: ‘How many astronomers have labored their whole lives on observations, and have not drawn a single conclusion.’[457] But the danger on the other side is so great and so ruinous that it cannot be enough insisted on, and indeed at times it makes all generalization suspicious and almost a thing to be eschewed: ‘I look at a strong tendency to generalize as an entire evil.’[458] At any rate, the theorist must never forget the subjective element, that his preconceptions and prejudices are apt to warp his judgment and distort his vision, till the keenest of observers and the sanest of thinkers may go astray: ‘the firmest conviction of the truth of a doctrine by its author seems, alas, not to be the slightest guarantee of truth.’[459]

The profit and the lesson of all which must be constantly borne home to oneself: ‘When I think of the many cases of men who have studied one subject for years, and have persuaded themselves of the truth of the foolishest doctrines, I feel sometimes a little frightened, whether I may not be one of these monomaniacs.’[460]

To appreciate fully Darwin’s combination of mental activity and fertility with moderation and restraint, it is well to place him between two extreme types of thinkers. On the one hand, there is the born essential reasoner, and logician, Spinoza, for instance, or Hegel, or Darwin’s own contemporary, Spencer, the man who to a greater or less extent takes fact for his foundation, but who by nature and temperament delights to weave an elaborate web of logical theory, rigid and perfect in its appearance of systematic deduction, but too apt in the end to treat facts with indifference if not disrespect. I like especially in this regard to compare Darwin with Lucretius. The De Rerum Natura is one of the most striking, enthralling examples of what I should call passionate thinking. Theoretical problems take hold of Lucretius like the ecstasies of love. He tears and wrenches at the roots of thought, determined to make them yield to the delving vigor of his eager search. Now Darwin has a broad and constant curiosity, his interest may well be called enthusiasm, and he himself uses the term passion for it: ‘Hence it has come to be a passion with me to try to connect all such facts by some sort of hypothesis.’[461] Yet in no phase of his nature should I be inclined ever to employ the general word, ‘passion,’ and it seems to me that every page of Lucretius is stamped with a devouring ardor different from anything Darwin knew.

On the other hand, over against these furious reasoners, I should set Darwin’s close contemporary, Sainte-Beuve, who, as I said in the previous chapter was, in some aspects, as admirable a representative of the scientific spirit as Darwin himself. The endless curiosity, the unlimited observation of fact, as embodied in the human subject, have never been more richly exemplified than in the great French critic. But Sainte-Beuve was no reasoner in the larger sense. He did not even avoid reasoning from mistrust: he had no taste for it, and when he dealt with it, it was always charily and with extreme reserve. He delighted to study and portray individuals and to allow those individuals, as it were, to classify themselves and so to point the way to general results.

Between these two extremes Darwin stands, as one who used reasoning to the fullest extent for the interpretation of fact, yet at the same time always stuck closely and rigidly to the fact itself, and would not allow it to be for an instant distorted by the reasoning process.

II

The supreme means for keeping theory on a basis of fact is of course unfailing, persistent, ever-varied experiment. In the preceding chapter we have seen observation lead naturally to experiment; but experiment is observation guided, directed, and illuminated by theory. And assuredly no scientist ever had the love and the habit of experiment more firmly fixed than Darwin. The explanation of phenomena was all very well in its place, essential, absorbing, but he would have agreed absolutely with Aristotle as to the proper ordering of the process: ‘After this we shall pass on to the discussion of causes. For to do this when the investigation of the details is complete, is the proper and natural method, and that whereby the subject and the premises of our argument will afterwards be rendered plain.’[462] The fascination of experiment in itself was endless and almost sufficing: ‘The love of experiment was very strong in him,’ says his son, ‘and I can remember the way he would say, “I shan’t be easy till I have tried it,” as if an outside force were driving him.’[463] There was a sense of adventure about it, of discovery, and he loved to try things that seemed almost fantastic and absurd: ‘If you knew some of the experiments (if they may be so-called) which I am trying, you would have a good right to sneer, for they are so absurd even in my opinion that I dare not tell you.’[464] And more concisely and vividly: ‘I am like a gambler and love a wild experiment.’[465] The best comment on which is the excellent remark of Professor Castle: ‘Most advances in practical affairs are made by those who have the courage to attempt what others with good reason think unattainable. When such attempts have succeeded, the world simply revises its classification of things attainable and unattainable, and makes a fresh start.’[466]

The first thing in regard to experiment is conditions. There are of course rough and elementary experiments, involving only simple principles, which do not require minute care in detail. But in many cases the nicest and most delicate preparation and adjustment are indispensable to ensure reliable results. The extensive equipment of modern laboratories was not at Darwin’s command, and though he had considerable financial resources, he could not afford the unlimited outlay of commercial research. Thus, we read of one of Mr. Burbank’s trials: ‘Forty thousand blackberry and raspberry hybrids were produced and grown until the fruit matured. Then from the whole lot a single variety was chosen as the best.... All others were uprooted with their crop of ripening berries, heaped up into a pile twelve feet wide, fourteen feet high, and twenty-two feet long, and burned. Nothing remained of this expensive and lengthy experiment, except the one parent plant of the new variety.’[467] Darwin could hardly work on any such elaborate scale as this. Yet, as one turns over his vast record of experiment, one is astonished to see how thorough and painstaking was his effort to avoid accidents and to provide for disturbing contingencies. Take, for instance, as a minor but significant illustration, his account of the difficulty in carrying out the specific fertilization of certain plants: ‘In making eighteen different unions, sometimes on windy days, and pestered by bees and flies buzzing about, some few errors could hardly be avoided. One day I had to keep a third man by me all the time to prevent the bees visiting the uncovered plants, for in a few seconds’ time they might have done irreparable mischief. It was also extremely difficult to exclude minute Diptera from the net.’[468]

Another vital consideration as to experiment, is that it should be kept impersonal. In most cases, if one is to experiment fruitfully and satisfactorily, there should be some special object in view, some particular point to be rejected or confirmed. Unless you know just what you are looking for, you are apt not to see. Again and again in Darwin’s book on Orchids, as in many of the others, we read that he made investigations and got no results, simply because he did not have in mind theoretical possibilities. When he had reasoned out what ought to happen or might happen, he often found that it did. The danger of this method is obvious. When the experimenter is so desperately anxious to see something, unless he is most carefully trained and disciplined, he will see it. It is not to be supposed that Darwin always escaped this danger, but few men have been more prepared for it or more ready to allow for it than he. His confession of prejudice, his recognition of the importance of certain points in his general theory and of his unwillingness to have anything interfere with them are among his greatest charms: ‘I remember well the time when the thought of the eye made me cold all over.... The sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick.’[469]

We have already enlarged under observation on the essential quality of accuracy, and it may simply be added that accuracy is doubly important in all experiments for a theoretical purpose. Accuracy, complete, detailed, mathematical exactitude, was Darwin’s hobby, and the minuteness of his record constantly exemplifies it.

Also, to confirm their accuracy experiments have to be repeated. Goethe remarks with justice that it is not necessary to travel all over the world to make sure that the sky is everywhere blue,[470] and no doubt there are repetitions that are vain and superfluous. But many difficult and delicate researches have to be gone over again and again that the minutest detail may be complete; and the process may involve months of tedious delay. Darwin’s unfailing care, both to repeat and to avoid repetition, is well indicated in his son’s comment: ‘Although he would patiently go on repeating experiments where there was any good to be gained, he could not endure having to repeat an experiment which ought, if complete care had been taken, to have succeeded the first time.’[471] Here too, one cannot appreciate how immense and thorough his experimentation was without looking through such books as the ‘Animals and Plants under Domestication’ or ‘The Power of Movement in Plants.’ The endless repetition of slightly varied combinations to test a difficult or remote conclusion makes one feel how persistent and inexhaustible the patience was. And after all the years of repeated and varied research and investigation he writes the almost pathetic epilogue six months before his death: ‘I wish that I had enough strength and spirit to commence a fresh set of experiments, and publish the results, with a full recantation of my errors when convinced of them.’[429]

Finally, experiments have to be not only made, but recorded, and the accuracy, so essential with all scientific observation, is above all essential here, since the omission of a link in the record may be ruinous to the continuity of the logical chain. It is peculiarly characteristic of Darwin that he wanted the record of error and mistake as well as of success. ‘I remember,’ says his son, ‘how strongly he urged the necessity of keeping the notes of experiments which failed, and to this rule he always adhered.’[430] The value of preserving and comparing apparently insignificant and meaningless notes is sometimes brought out, as in a special case of orchids: ‘I had given up the case as hopeless, until summing up my observations, the explanation presently to be given, and subsequently proved by repeated experiments to be correct, suddenly occurred to me.’[431] Long experience of his own mistakes and failures induces extreme scepticism as to the results of others: ‘The difficulty is to know what to trust.’[352] Even when he has taken the greatest pains, the scepticism often lingers and forces him to repeat although with an identical result: ‘Notwithstanding the care taken and the number of trials made, when in the following year I looked merely at the results, without reading over my observations, I again thought that there must have been some error, and thirty-five fresh trials were made with the weakest solution; but the results were as plainly marked as before.’[353] And thus the long series of packed, closely printed volumes forms an amazing record of a life of zealous, persistent, curious experimentation from beginning to end.

III

Now let us look a little more closely at the stuff and quality of Darwin’s logical processes, considered as such. He himself often complains of the slowness and difficulty of his thinking. It is hard for him to arrange his thoughts, he says, hard for him to get them into the lucid and effective order which carries conviction with it, almost enforces conviction by the power of its own movement. He says of one of his critics: ‘He admits to a certain extent Natural Selection, yet I am sure does not understand me. It is strange that very few do, and I am become quite convinced that I must be an extremely bad explainer.’[354]

It is worth while to note the comments of Huxley, as one of Darwin’s staunchest friends and supporters, on his reasoning faculty and processes. When Romanes lauds Darwin’s colossal intellect, Huxley is inclined to protest: ‘Colossal does not seem to me to be the right epithet for Darwin’s intellect. He had a clear, rapid intelligence, a great memory, a vivid imagination, and what made his greatness was the strict subordination of all these to the love of truth.’[355] Elsewhere Huxley adds: ‘Exposition was not Darwin’s forte—and his English is sometimes wonderful. But there is a marvelous dumb sagacity about him and he gets to truth by ways as dark as those of the Heathen Chinee.’[356] Of ‘The Origin of Species’ Huxley writes: ‘It is one of the hardest books to understand thoroughly that I know of.’[357] And again, more amply: ‘Long occupation with the work has led the present writer to believe that “The Origin of Species” is one of the hardest of books to master, and he is justified in this conviction by observing that although the “Origin” has been close on thirty years before the world, the strangest misconceptions of the essential nature of the theory therein advocated are still put forth by serious writers.’[358] Critics less friendly to Darwin than Huxley have spoken still more strongly.

I feel that Huxley’s judgment is too severe. It is true that Darwin had not the admirable gift of logical, lucid exposition which made Huxley himself one of the most luminous of scientific writers. But even when Darwin’s reasoning is most complex and difficult, there is a notable quality of sincerity and single-mindedness, which wins and retains your confidence. He seems somehow to have an exceptional power of taking you into his mental processes, and to make you think and see and feel as he does. If you feel that he may be wrong, it is because he feels that he may be wrong himself.

It is profitable to examine a little more in detail some illustrations of Darwin’s scientific theorizing. The great central doctrine of evolution, with its buttressing support of natural selection, will fill our next chapter, but there are several lesser developments of speculation which deserve notice. I need hardly say that we are not in any way discussing the validity of the theories in the abstract, but simply Darwin’s fashion of framing, holding, and sustaining them.

There is first the theory as to the formation of coral reefs. At an early period in his career Darwin conceived the idea that these reefs were produced by the subsidence of the ocean bed and the steady building up of the coral insects toward the surface. He himself admits that this theory was the most deductive of all that he ever urged and the least founded in the beginning upon a wide and careful investigation of fact. Alexander Agassiz, who, after extensive research, was not disposed to accept it, wrote: ‘Darwin’s observations were all theoretical, based upon chartographic study in his house, a very poor way of doing, and that’s the way all his coral reef work has been done.’[359] And the theory has met with strenuous opposition from many quarters, though one critic says in regard to it: ‘Be it true or not, be it a competent explanation or not, no matter. In influence on geology it has been as far-reaching as the doctrine of natural selection has been on biology.’[360] But Darwin himself clung to it to the end, meeting objections with vast ingenuity and reiterating his positions with ampler and more penetrating arguments. Yet through all the persistence there is the readiness at any moment to see the other side. ‘I must still adhere to my opinion, that the atolls and barrier reefs in the middle of the Pacific and Indian Oceans indicate subsidence, but I fully agree with you that such cases as that of the Pellew Islands, if of at all frequent occurrence, would make my general conclusions of very little value. Future observers must decide between us.’[361] And he writes frankly to Alexander Agassiz: ‘If I am wrong, the sooner I am knocked on the head and annihilated so much the better.’[362]

Another instance of Darwin’s zeal and ingenuity in reasoning is the theory of sexual selection, devised to meet some difficulties in his general argument. Many animals have certain so-called secondary sexual characteristics, that is, characteristics affecting one sex only yet not directly involved in the reproductive process. Darwin believed that these characteristics were largely developed through the working of natural selection upon the basis of the preference of one sex for individuals of the other for mating purposes. That is to say, the splendor of the male peacock’s tail made him more attractive to the female and therefore more successful with her. There were numerous and obvious difficulties in this view, as the assumption of a fine æsthetic sense in comparatively lowly organized creatures, and it was energetically disputed from the start. Wallace, Darwin’s ardent fellow-thinker and coadjutor, was anything but favorable to it. Yet Darwin’s faith was never really shaken. He persisted to the end, making new experiments and investigations, and meeting his adversaries’ contentions with vast and varied resource. In ‘The Descent of Man’ he wrote: ‘For my own part I conclude that of all the causes which have led to the differences in external appearance between the races of man, and to a certain extent between man and the lower animals, sexual selection has been the most efficient.’[363] Nevertheless, it is fascinating to see him reveal the doubt and the questioning that were inwrought with conviction in his mind. He writes to Wallace: ‘I grieve to differ from you, and it actually terrifies me and makes me constantly distrust myself.’[364] Again: ‘You will be pleased to hear that I am undergoing severe distress about protection and sexual selection; this morning I oscillated with joy towards you; this evening I have swung back to my [old] position, out of which I fear I shall never get.’[365] And he sums up the process with a general remark of the largest and most fruitful bearing: ‘I sometimes marvel how truth progresses, so difficult is it for one man to convince another, unless his mind is vacant. Nevertheless, I myself to a certain extent contradict my own remark, for I believe far more in the importance of protection than I did before reading your articles.’[366]

Still another example of theorizing is the doctrine of pangenesis. Darwin’s general theory of evolution which dealt so much with heredity, was closely complicated with the difficulty of understanding how one minute reproductive cell could transmit by inheritance all the complicated variety of organs and functions in a highly developed plant or animal. To meet this difficulty he devised the explanation of pangenesis (he doubts about the name, because ‘my wife says it sounds wicked, like pantheism’),[367] that is, the idea that the primitive cell contains a great number of gemmules, each transmitting and originating some particular organ with its varied functions. Here again the theory, as Darwin conceived it, did not find general acceptance, though in some respects it surprisingly anticipates the results of the latest modern research. But the interesting thing is to see the ardor with which its inventor worked it out and the elaborate argument with which he carries it through the latter part of the great work on ‘Animals and Plants under Domestication.’ It is difficult, he admits. He does not blame any one for disputing it, or for rejecting it, or even for laughing at it. ‘The hypothesis of Pangenesis, as applied to the several great classes of facts just discussed, no doubt is extremely complex, but so are the facts.’[368] And then he lets his imagination range more widely than usual in contemplating possible deductions and consequences: ‘No other attempt, as far as I am aware, has been made, imperfect as this confessedly is, to connect under one point of view these several grand classes of facts. An organic being is a microcosm—a little universe, formed of a host of self-propagating organisms, inconceivably minute and numerous as the stars in heaven.’[369] Yet here again he introduces the inevitable reservation and in his Autobiographical Sketch he says: ‘Towards the end of the work I give my well-abused hypothesis of Pangenesis. An unverified hypothesis is of little or no value; but if any one should hereafter be led to make observations by which some such hypothesis could be established, I shall have done good service.’[370]

It seems sometimes surprising that, with this marked bent towards abstract speculation, which it was so difficult to control, Darwin should have been always so indifferent to philosophical thought on the ultimate questions of the universe. He admits that he knew little of metaphysics and cared little for them. But this again is instructive as to the peculiar balance of his temperament. He liked to speculate, but he would not speculate for a moment without a firm foundation of fact. His feet must be based first on the solid tangible earth. Then if his head would not reach the clouds, he would keep out of them.

IV

It will be profitable to consider more in detail some specific elements of Darwin’s reasoning. In the first place, we have seen everywhere and in all connections that his propensity to eager theorizing was tempered with an unfailing sense of doubt and mistrust. He was indeed always disposed to act in the spirit of Weisman’s remark: ‘When we are confronted with facts which we see no possibility of understanding save on a single hypothesis, even though it be an undemonstratable one, we are naturally led to accept the hypothesis, at least until a better one can be found.’[371] And he recognized fully the force of the comment which Huxley makes on a phrase of Goethe, to the effect that doubt must not be blighting or destructive, but fruitful and stimulating: ‘Goethe has an excellent aphorism defining that state of mind which he calls “Thätige Skepsis”—active doubt. It is doubt which so loves truth that it neither dares rest in doubting nor extinguish itself by unjustified belief.’[64] At the same time, the doubt was there, was temperamental, and could not be altogether extinguished, even when the rush of the logical impetus was fullest. One beautiful expression of it among many is, ‘When you say you cannot master the train of thoughts, I know well enough that they are too doubtful and obscure to be mastered. I have often experienced what you call the humiliating feeling of getting more and more involved in doubt the more one thinks of the facts and reasoning on doubtful points.’[65] The truth is, that Darwin had in a high degree the quality, often so hampering to the man of practical action, but invaluable to the thinker, of getting outside of himself and his own point of view and criticizing it as if it were the standpoint of some one else. He himself indicates this forcibly in connection with returning to one’s ideas after an interval: ‘The delay in this case, as with all my other books, has been a great advantage to me; for a man after a long interval can criticize his own work, almost as well as if it were that of another person.’[66] Some men can.

Another characteristic of Darwin’s mental processes is his way of meeting difficulties. The born reasoner is apt to slur over obstacles and objections, to devote himself with endless ingenuity to eliminating them rather than facing them squarely. Darwin was ingenious enough, but he did not dodge difficulties. Instead of doing so, his propensity was, if anything, to make them and seek them. It was said of Pasteur, so like Darwin in many points: ‘No adversary of M. Pasteur had formulated this argument; but M. Pasteur, who had within himself an ever-present adversary, always on the watch and determined to yield only to the force of accumulated evidence, himself raised the objection.’[67] So Darwin. As he himself records, and no thinker ever laid down a more significant principle or one more revealing for his own mental constitution: ‘I had, also, during many years followed a golden rule, namely, that whenever a published fact, a new observation or thought came across me, which was opposed to my general results, to make a memorandum of it without fail and at once; for I had found by experience that such facts and thoughts were far more apt to escape from the memory than favorable ones.’[68] And the intense consciousness of objections and difficulties appears even more vividly in the sentence: ‘I cannot too strongly express my conviction of the general truth of my doctrines, and God knows I have never shirked a difficulty.’[69]

The recognition of obstacles and complications constantly popping up from everywhere naturally necessitated endless revision and recasting. Here again, the habitual reasoner, having once set his mould is reluctant to alter it. Not so Darwin. There are indeed times when even he rebels and declares that it will be more fruitful to follow new paths than to be perpetually adjusting the old. But in general his readiness to alter and reconstruct is unlimited. He revises and works over his books. In doing so he showed his characteristic disposition to accept and defer to the judgment of others. How charming is his daughter’s account of this: ‘He was always so ready to be convinced that any suggested alteration was an improvement, and so full of gratitude for the trouble taken. I do not think that he ever used to forget to tell me what improvement he thought that I had made, and he used almost to excuse himself if he did not agree with any correction. I think I felt the singular modesty and graciousness of his nature through thus working for him in a way I never should otherwise have done.’[70] There is no better way to appreciate the extent and the persistence of Darwin’s revision than to make even a cursory comparison of the first and the last editions of the ‘Origin.’ Almost every page shows minor or considerable changes, and while some are no doubt mere matters of language, many have a bearing, however slight, on the trend of the reasoning, deepening, or strengthening, or clarifying it.

It is profitable also to watch Darwin’s attitude towards argument, the direct interchange of view by those who take different sides of a case and are at once eager to advance their own and to detect the flaws in their opponent’s. It is very evident that he was not a quick and natural arguer, as was Huxley, for instance. His son says: ‘He used to say of himself that he was not quick enough to hold an argument with any one, and I think this was true. Unless it was a subject on which he was just then at work, he could not get the train of argument into working order quickly enough.’[71] And Darwin confesses the same thing with his unfailing, charming naïveté, in a letter to Hooker: ‘I am astonished at your success and audacity. It is something unintelligible to me how any one can argue in public like orators do. I had no idea you had this power.’[72]

Arguments haunted him, agitated him, disturbed him. Active discussion was apt to be followed by a broken night, filled with the things that might and should have been said and were not. Even of a conversation quite remote from his scientific interest he says: ‘Your slave discussion disturbed me much; but as you would care no more for my opinion on this head than for the ashes of this letter, I will say nothing except that it gave me some sleepless, most uncomfortable hours.’[73]

The gift I have before suggested, of getting outside of your own position and judging it as another would, while it benefits the results of argument, is most hampering in the process, since one finds oneself stating one’s adversary’s case sometimes more forcibly than he does himself. Darwin often repeats the principle I have quoted earlier, of recognizing and recording objections, and he sums up his method in regard to his main theory: ‘I have for some time determined to give the arguments on both sides (as far as I could) instead of arguing on the mutability side alone.’[74]

Yet in spite of all the strain and effort of argument, he liked it and believed in it. In the concluding chapter of the ‘Origin’ he says: ‘This whole volume is one long argument.’[75] It certainly is. Elsewhere he says of a personal conversation: ‘I was particularly glad of our discussion after dinner; fighting a battle with you always clears my mind wonderfully.’[76] To get the mind clear, to illuminate and elucidate the complicated tangles of thought and theory, that was always the object, and if verbal battles helped it on, they were welcome.

But if he liked sincere, earnest argument, he detested controversy, the bitter war of excited personal feelings bent rather on achieving an individual triumph than on proving an abstract theory. He condemned and deplored the injury to science inevitably wrought by such disputes and had nothing but disgust for the manifestations of temper that were bound to accompany them: ‘I went the other evening to the Zoölogical Society, where the speakers were snarling at each other in a manner anything but like that of gentlemen.’[77]

When his own views were involved in bitterness, as, alas, they too often were, he expressed the keenest regret: ‘I often think that my friends ... have good cause to hate me, for having stirred up so much mud, and led them into so much odious trouble. If I had been a friend of myself, I should have hated me.’[78] He early made up his mind to keep out of quarrels if possible, and he congratulated himself on the whole on his success: ‘I rejoice that I have avoided controversies, and this I owe to Lyell, who many years ago, in reference to my geological works, strongly advised me never to get entangled in a controversy, as it rarely did any good and caused a miserable loss of time and temper.’[79]

Thus, whenever it was possible, he shunned dispute, and if, by any chance, haste and eagerness involved him in a mistaken cause, he bitterly regretted his blunder and was ready to acknowledge it with the utmost frankness. One of the most striking cases of this is that of the parallel roads of Glen Roy, as to which Darwin had developed a geological theory which he asserted with a good deal of conviction. A careful consideration of his opponent’s arguments, obliged him to recognize that he was completely in the wrong, and he gave up, though with a pang: ‘I am very poorly to-day, and very stupid, and hate everybody and everything. One lives only to make blunders.’[80] His acknowledgment of his error was ample and complete.

It was his natural frankness in admitting his mistakes and endeavoring to rectify them which made Darwin so attractive and engaging. Goethe complains of the disposition of many people to reiterate a misstatement because they have once made it.[81] Such reiteration did not appeal to Darwin in the least. Sometimes he was irritated and annoyed by the attitude of his adversaries, and he expressed the annoyance with the same outspokenness that he gave to other things; but there was never any attempt to conceal his blunders or to maintain his own positions simply because they were his.

Indeed, in this regard, as in all others, what distinguished him was a singular and charming candor. It is this which makes his letters so attractive and so revealing. They are not great literary letters. They are always written in haphazard fashion and with the utmost casual directness. But few correspondences of literary men or of any others reveal the man with such clear and winning amplitude. He opens his heart and leads you right into it without the least pretence of self-revelation, but simply as if he were thinking aloud to you, as he is. Take, for instance, among a bewildering mass of illustrations, his confession of the sense of inferiority in regard to Spencer: ‘I feel rather mean when I read him: I could bear, rather enjoy feeling that he was twice as ingenious and clever as myself, but when I feel that he is about a dozen times my superior, even in the master art of wriggling, I feel aggrieved.’[82] Or this other acknowledgment to Hooker: ‘How candidly and meekly you took my Jeremiad on your severity to second-class men. After I had sent it off, an ugly little voice asked me, once or twice, how much of my noble defence of the poor in spirit and in fact, was owing to your having not seldom smashed favorite notions of my own. I silenced the ugly little voice with contempt, but it would whisper again and again.’[83] The sense, the atmosphere, of a pervading candor, was what Huxley expressed so excellently when he spoke of Darwin’s having ‘a certain intense and almost passionate honesty by which all his thoughts and actions were irradiated, as by a central fire. It was this greatest and rarest of endowments which kept his vivid imagination and great speculative powers within due bounds ... which made him accept criticisms and suggestions from anybody and everybody, not only without impatience, but with expressions of gratitude sometimes almost comically in excess of their value.’[84]

For the honesty and the candor not only led him to admit his own mistakes, but made him singularly ready to recognize the merits of others, and to tolerate not only their views but even their dogmatic assertion of them. He made mistakes all the time, and yet he knew that he was sincere and lofty in purpose. Why should not others be the same? Why should not their theories be right and his wrong? ‘It matters very little to any one except myself, whether I am a little more or less wrong on this or that point; in fact, I am sure to be proved wrong on many points.’[85] Of one who did not agree with him he could say: ‘I know nothing of him excepting from his letters: these show remarkable talent, astonishing perseverance, much modesty, and what I admire, determined difference from me on many points.’[86] And how winning is his defense of blunderers, of those who do poor work which is not all poor: ‘Shall you think me very impudent if I tell you that I have sometimes thought that ... you are a little too hard on bad observers; that a remark made by a bad observer cannot be right; an observer who deserves to be damned you would utterly damn. I feel entire deference to any remark you make out of your own head; but when in opposition to some poor devil, I somehow involuntarily feel not quite so much.’[87]

The truth is, that Darwin’s tolerance was based, as all real tolerance is apt to be, on the vast and haunting sense of his own ignorance. Again and again he repeats and emphasizes how little he knows, how little any one knows, and how petty, imperfect, and inadequate are the efforts of any and all of us to penetrate the veil of shrouding mystery which involves the deepest secrets of life. To probe this mystery the vague and flickering torch of reason is all that is given to us. And those who are most conversant with reason and make most use of it mistrust it most. When the far surer guidance of instinct fails us, reason is our only support, and we must employ it not only for the larger speculative purposes, but for the practical decisions. At its best, it is a bright and splendid instrument, incredibly keen and penetrating, and able to accomplish miracles in the hands of those who manipulate it skillfully. But it is an instrument as delicate as it is bright, and it loses point and edge, unless constant pains are taken to keep it in working condition. Also, it cuts both ways, and every way, and to even the expert manipulator, perhaps to him most of all, it is apt to be difficult, dangerous, treacherous.

There is the subtle, unfathomable connection of reason with our wishes, desires, and prejudices. A clever Frenchman said that reason was given us to enable us to justify the gratification of our passions, and when we see how the devices of logic may be used to work from any premises to any conclusion, one feels the force of the Frenchman’s view.

No one was more aware than Darwin of these dangers and difficulties of reason, or of the endless possibilities of deception when one gives oneself up to that enchanting and deluding siren. He often emphasizes his distress and almost despair at finding himself making deductions quite different from those which others draw from the same facts. ‘It is really disgusting and humiliating to see directly opposite conclusions drawn from the same facts.’[88] And again: ‘Nothing is so vexatious to me, as so constantly finding myself drawing different conclusions from better judges than myself, from the same facts.’[89] And yet again: ‘I hate beyond all things finding myself in disagreement with any capable judge, when the premises are the same.’[90]

These comments make us see clearly what Darwin’s relation to reason was. Few thinkers have been so ready, so fertile, so abundant, so ingenious, yet at the same time so sober, so restrained and controlled.

With this analysis of his observation and his thought we are ready to take up the supreme interest of Darwin’s life, the dramatic study of the conception, elaboration, promulgation, and triumph of his evolutionary theory.