But besides the direct action of outward things on the senses, he admits the power of certain images to make themselves immediately present to the mind (iv. 722-822), and also a certain immediate apprehension or intuition of the mind (iniectus animi) into things beyond the cognisance of sense²⁰. Thus there is no actual inconsistency with his principles in claiming the power of understanding the properties and configuration of the atoms, which are represented as lying below the reach of our senses—

But of the mode of operation of this 'intuition of the mind' there is no criterion. The doctrine of the properties, shapes, motions, etc. of the atoms is a creation of the imagination, suggested by certain analogies from sensible things, but incapable of being verified by the senses, which he regards as the only sure foundations of knowledge.

But even on the supposition that the existence and properties of the atoms had been satisfactorily established, no adequate explanation is offered of their relation to the facts of existence. The same difficulty is encountered at the outset of this as of all other ancient systems of ontology, viz. how to pass from the eternal and immutable forms of the atoms to the variety and transitory nature of sensible objects. This is the very difficulty which Lucretius himself urges against the system of Heraclitus,—

The order of Nature now subsisting is declared to be the result of the manifold combination of the atoms through infinite time and space, but the intermediate stages by which this process was effected are assumed rather than investigated. We seem to pass 'per saltum' from the chaos of lifeless elements to the perfect order and manifold life of our system. This wide chasm seems as little capable of being bridged by the help of the atoms of Democritus, as by the watery element of Thales or the fiery element of Heraclitus. But in Lucretius this difficulty is partially concealed, by a poetical element in his conception, really inconsistent with the mechanical materialism on which his philosophy professes to be based.—It is to be observed that while the Greek word ἄτομα implies merely the notion of individual existences, the words used by Lucretius, 'semina,' 'genitalia corpora,' really indicate a creative capacity in these existences. In conceiving their power of carrying on and sustaining the order of Nature, his imagination is thus aided by the analogy of the growth of plants and living beings. A secret faculty in the atoms, distinct from their other properties, is assumed. Thus he says—

In his statement of the doctrine of the Clinamen, or slight declension in the motion of the atoms, so as 'to break the chain of fate,' he attributes to them a power analogous to volition in living beings. This doctrine is suggested by the necessity of explaining contingency in Nature and freedom in the movements of sentient beings. We are, as in all attempts to account for creation, forced back on the thought of an ultimate unexplained power in virtue of which things have been created and are maintained in being.

The Lucretian hypothesis of the atoms, even if it were accepted as the most reasonable explanation of the original constitution of matter, is, by itself, altogether inadequate as a key to the secret of Nature. It cannot be shown either how these atoms succeeded in arranging themselves in order, or how from their negative properties all positive life has been produced. The explanation of physical phenomena given in the four last books, as to the nature of our bodies and souls,—as to the action of outward things on the senses,—the origin and existence of the sun and moon, the earth and the living beings upon it, etc., although professedly deduced from the principles established in the first two books, are really reached independently. They are either immediate inferences from the obvious intimations of sense, or they are the suggestions of analogy.

The weakness as well as the strength of ancient science lay in its perception of analogies. The mind of Lucretius was both under the influence of earlier analogical conceptions, and also shows great boldness and originality in the logical and poetical apprehension of 'those same footsteps of Nature, treading on diverse subjects or matters.' But, in common with the earlier enquirers of Greece, he trusts too implicitly to their guidance through all his daring adventure. He seems to believe that the hidden properties of things are as open to discovery through this 'lux sublustris' of the imagination, as through the 'lucida tela' of the reason.

To take one prominent instance of this influence, it is remarkable how, in his explanation of our mundane system, he is both consciously and unconsciously guided by the analogy of the human body. Even Lucretius, living in the very meridian of ancient science, cannot in imagination absolutely emancipate himself from the associations of mythology. He is indeed conscious of the inconsistency of attributing life and sense to the earth: yet not only does he speak poetically of Earth being the creative mother, Aether the fructifying father of all things, but his whole conception of the creation of the world is derived from a supposed likeness between the properties of our terrestrial and celestial systems, and those of living beings. Thus we read—

Of the growth of plants and herbage it is said—

From v. 535 to 563 the power of the air in supporting the earth 'in media mundi regione' is compared with the power which the delicate vital principle has in supporting the human body. Again, the gathering together of the waters of the sea is thus represented—

And finally, though it would be easy to multiply such quotations, the striking account, at the end of the second book, of the growth and the decay of our world is drawn directly from the obvious appearances of the growth and decay of the human body; e.g.—

As a necessary result of a system of natural philosophy based on assumptions, largely illustrated indeed, but not corroborated by the observation of phenomena, with no verification of experiment or ascertainment of special laws, there is throughout the poem the utmost hardihood of assertion and inference on many points, on which modern science clearly proves this system to have been as much in error as it was possible to be. It is strange to note how inadequate an idea Lucretius had of the vastness and complexity of the problem which he professed to solve. He has no real conception of the progressive advance of knowledge, and of the necessity of patiently building on humble foundations. The striking lines—

look rather like an unconscious prophecy of the future progress of science than an account of the process of enquiry exhibited in the book.

A few out of many erroneous assertions about physical facts, in regard to some of which the opinions of Lucretius are behind the science even of his own time, may be noticed. Thus, at i. 1025, the existence of the Antipodes is denied. Again, in Book iii. the mind is stated to be a material substance, seated in the centre of the breast, composed of very minute particles, the relative proportions of which determine the characters both of men and animals. Lucretius shows a close and subtle observation of facts that establish the interdependence of mind and body, but no suspicion of that interdependence being connected with the functions of the brain and nervous system. His whole account of the mundus, of the earth at rest in the centre, and of the rolling vault of heaven, with its sun and moon and stars—'trembling fires in the vault'—all no larger than they appear to our eyes, is given without any notion of the inadequacy of his data to bear out his conclusions. The science which satisfied Epicurus was on astronomical and meteorological questions behind that attained by the mathematicians of Alexandria: and thus some of the conclusions enunciated by Virgil in the Georgics are nearer the truth than those accepted by Lucretius. While enlarging on the variety and subtlety in the combinations of his imaginary atoms, he has no adequate idea of the variety and subtlety in the real forces of Nature. His observation of the outward and visible appearances of things is accurate and vivid: there is often great ingenuity as well as a true apprehension of logical conditions in his processes of reasoning both from ideas and from phenomena: yet most of his conclusions as to the facts of Nature, which are not immediately perceptible to the senses, are mere fanciful explanations, indicating, indeed, a lively curiosity, but no real understanding of the true conditions of the enquiry. The root of his error lies in his not feeling how little can be known of the processes and facts of Nature by ordinary observation, without the resources of experiment and of scientific method built upon experiment.

The weak points of this philosophy, the mistaken aim and incomplete method of enquiry, the real ignorance of facts disguised under an appearance of systematic treatment, the unproductiveness of the results for any practical accession to man's power over Nature, are quite obvious to any modern reader, who, without any special study of physical science, cannot help being familiar with information which is now universally diffused, but which was beyond the reach of the most ardent enquirers and original thinkers of antiquity. But the amount of information possessed by different ages, or by different men, is no criterion of their relative intellectual power. The mental force of a strong and adventurous thinker may be recognised struggling even through these mists of error. The weakness of the system, interpreted by Lucretius, is the necessary weakness of the childhood of knowledge. But along with the weakness and the ignorance there are also the keen feeling, the clear eye, and the buoyant fancies of early years,—the germs and the promise of a strong maturity.

The full light in which ancient poetry, history, and mental philosophy can still be read, makes us apt to forget that a great part even of the intellectual life of antiquity has left scarcely any record of itself. Of one aspect of this intellectual life Lucretius is the most complete exponent. The genius of Plato and Aristotle has been estimated, perhaps, as justly in modern as in ancient times. But the great intellectual life of such men as Democritus, Empedocles, or Anaxagoras, escapes our notice in the more familiar studies of classical literature. The work of Lucretius reminds us of the intensity of thought and feeling, the clearness and minuteness of observation, with which the earliest enquiries into Nature were carried on. In some respects the general ignorance of the times enhances our sense of the greatness of individual philosophers. Each new attempt to understand the world was an original act of creative power. The intellectual strength and enthusiasm displayed by the poet himself may be regarded as some measure of the strength of the masters, who filled his mind with affection and astonishment.

The history of the physical science of the ancients cannot, indeed, be regarded as so interesting or important as that of their metaphysical philosophy. And this is so, not only on account of the comparative scantiness of their real acquisitions in the one as compared with the ideas and method which they have contributed to the other, and with the masterpieces which they have added to its literature; but still more on this account, that in physical knowledge new discovery supplants the place of previous error or ignorance, and can be understood without reference to what has been supplanted; whereas the power and meaning of philosophical ideas is unintelligible, apart from the knowledge of their origin and development. The history of physical science in ancient times affords satisfaction to a natural curiosity, but is not an indispensable branch of scientific study. The history of ancient mental philosophy, on the other hand,—the source not only of most of our metaphysical ideas and terms, but of many of the most familiar thoughts and words in daily use,—is the basis of all speculative study. Yet among the various kinds of interest which this poem has for different classes of modern readers this is not to be forgotten, that it enables a student of science to estimate the actual discoveries, and, still more, the prognostications of discovery attained by the irregular methods of early enquiry. The school of philosophy to which Lucretius belonged was distinguished above other schools for the attention which it gave to the facts of Nature. Though he himself makes no claim to original discovery, he yet shows a philosophical grasp of the whole system which he adopted, and a rigorous study of its details. He does not, like Virgil, merely reproduce some general results of ancient physics, to enhance the poetical conception of Nature: as he is not satisfied with those general results about human life and the origin of man, which amused a meditative poet and practical epicurean like Horace. He was a real student both of the plan of Nature and of man's relation to it. Out of the stores of his abundant information the modern reader may best learn not only the errors but also the happy guesses and pregnant suggestions of ancient science.

To the general reader there is another aspect, in which it is interesting to compare these germs of physical knowledge with some tendencies of scientific enquiry in modern times. The questions, vitally affecting the position of man in the world, which are discussed or raised by Lucretius in the course of his argument, are parallel to certain questions which have risen into prominence in connexion with the increasing study of Nature. Most conspicuous among these is the relation of physical enquiry to religious belief. Expressions such as this,

show that scientific enquiry had to encounter the same prejudice in ancient as in modern times. The insufficiency and audacity of human reason were reprobated by the antagonists of Lucretius as they often are in the present day. Ancient religion denounced those who investigated the origin of sun, earth, and sky, as

The views of Lucretius as to the natural origin of life, and the progressive advance of man from the rudest condition by the exercise of his senses and accumulated experience,—his denial of final causes universally, and specially in the human faculties,—his resolution of our knowledge into the intimations of sense,—his materialism and consequent denial of immortality,—and his utilitarianism in morals,—all present striking parallels to the opinions of one of the great schools of modern thought. At v. 875 there is a passage concerning the preservation and destruction of species, originally suggested by Empedocles,—which shows that the idea of the struggle for existence and of the survival of those species best fitted for the conditions of that struggle was familiar to ancient thinkers. It is there observed that those species alone have escaped destruction which possess some natural weapon of defence, or which are useful to man. Of others that could neither live by themselves nor were maintained by human protection, it is said—

The attempt to trace the origin of all supernatural belief to the impressions made by dreams, the explanation given of the first manifestation of the humaner sentiments, of the beginning of language, and of the whole condition of 'primitive man,' are in conformity with the teaching of the most popular exponent of the doctrine of evolution in the present day.

But altogether apart from the truth and falsehood, the right and wrong tendencies of his system of philosophy, our feeling of personal interest in the poet is strengthened by noting the power of reasoning, observation, and expression put forth by him through the whole course of his argument. The pervading characteristic of Lucretius is the 'vivida vis animi.' The freshness of feeling and vividness of apprehension denoted by the words,

are as remarkable in the processes of his intellect as of his imagination.

The passionate intensity of his nature has left its impress on the enunciation of his physical as well as of his moral doctrines. He has a thoroughly logical grasp of his subject as a whole. He shows the capacity of unfolding it and marshalling all his arguments in symmetrical order, and of arranging in due subordination vast masses of details. Vigour in acquiring and tenacity in retaining the knowledge of facts are combined with a high organising faculty. He has also, beyond any other Roman writer, a power of analysing and comprehending abstract ideas, such as that of the infinite, of space and time, of causation and the like, and of keeping the consequences involved in these ideas present to his mind through long-sustained processes of reasoning. He alone among his countrymen possessed, if not the faculty of original speculation, the genuine philosophic impulse, and the powers of mind demanded for abstruse and systematic thinking.

This vigour of understanding is displayed in many processes of deductive reasoning, in the power of seizing some general principle underlying diverse phenomena, in the use of analogies by which he illustrates the argument and advances from known to unknown causes and from things within the cognisance of our senses to those beyond their range, and in the clearness and variety of his observation.

His system cannot be called either purely inductive or purely deductive, though it is more of the former than of the latter. He argues with great force both from a large and varied mass of facts to general laws and from general principles to facts involved in them. The best examples of his power of following abstract ideas into their consequences may be found in the first two books, where he establishes the existence of vacuum, the infinity of space and of the atoms, the limitations of the form of the atoms and the like. The reasoning at i. 298-328 where the existence of invisible bodies is established affords a good instance of his power of recognising a common principle involved in a great number and variety of phenomena.

The vigour with which he reasons from known to unknown facts and causes may be judged most fairly by his arguments on the progress of society, where he is more on an equality with modern speculation. He discards, altogether, as might be expected, the fancies concerning a heroic or a golden age, and assumes as his data the facts of human nature as observed in his own day. The grounds from which he starts, his method of reasoning, and the nature of his conclusions remind a reader of the positive tendencies of Thucydides, as they are displayed in the introduction to his history. The importance of personal qualities, such as beauty, strength, and power of mind, in the earliest stage of civil society, the influence of accumulated wealth at a later period, the causes of the establishment and overthrow of tyrannies and of the rise of commonwealths in their room, are all set forth with a degree of strong sense and historical sagacity, such as no other Roman writer has shown in similar investigations. The inferiority even of Tacitus in his occasional digressions into the philosophy of history is very marked. On such topics, where the data were accessible to the natural faculties of observation and inference, and where conclusions were sought which, without aiming at definite certainty, should yet be true in the main, the reader of Lucretius has no sense of that wasted ingenuity which he often feels in following the investigations into some of the primary conditions of the atoms, the component elements of the soul, the process by which the world was formed, or the causes of electric or volcanic phenomena.

Lucretius makes a copious, and often a very happy use, of analogies, both in the illustration of his philosophy, and in passages of the highest poetical power. Some of the most striking of the former kind have already been noticed as sources of error, or at least of disguising ignorance, in his reasoning, viz. those founded on the supposed parallel between the world and the human body; others again are employed with force and ingenuity in support of various positions in his argument. Among these may be mentioned his comparison of the effect of various combinations of the same letters in forming different words, with that of the various combinations of similar atoms in forming different objects in nature. So too the ceaseless motion of the atoms is brought visibly before the imagination by the analogy of the motes dancing in the sunbeam. There is something striking in the comparison of the human body immediately after death to wine 'cum Bacchi flos evanuit,' and again, in that of the relation of body and soul to the relation of frankincense and its odour—

But this faculty of his understanding is in general so united with the imaginative feeling through which he discerns the vital identity of the most diverse manifestations of some common principle, that it can best be illustrated in connexion with the poetical, as distinct from the logical, merits of the work.

So also it is difficult to separate his faculty of clear, exact, and vivid observation from his poetical perception of the life and beauty of Nature. His powers of observation were, however, stimulated and directed by scientific as well as poetic interest in phenomena. From the wide scope of his philosophy he was led to examine the greatest variety of facts, physical as well as moral. His sense of the immensity of the universe led him to contemplate the largest and widest operations of Nature,—such as the movements of the heavenly bodies, the recurrence of the seasons, the forces of great storms, volcanoes, etc.; while, again, the theory of the invisible atoms drew his attention to the minutest processes of Nature, in so far as they can be perceived or inferred without the appliances of modern science. Thus, for instance, in a long passage beginning—

he shows by an accumulation of instances that there are many invisible bodies, the existence of which is inferred from visible effects. In other places he draws attention to the class of facts which have been the basis of the modern science of geology,—such as the mark of rivers slowly wearing away their banks,—of walls on the sea-shore mouldering from the long-continued effects of the exhalations from the sea,—of the fall of great rocks from the mountains under the wear and tear of ages.

Again, the argument is frequently illustrated by observation of the habits of various animals. In these passages Lucretius shows the curiosity of a naturalist, as well as the sympathetic feeling and insight of a poet. How graphic, for instance, is his description of dogs following up the scent of their game—

How happily their characteristics are struck off in the line—

The various cries and habits of birds are often observed and described, as—

and again—

The description of sea-birds,

recalls the vivid and natural life of those that haunted the isle of Calypso—

His lively personal observation and active interest in the casual objects presented to his eyes in the course of his walks are seen in such passages as—

There is also much truth and liveliness of observation in his notices of psychological and physiological facts; as in those passages where he establishes the connexion between mind and body, and in his account of the senses. With what a graphic touch does he paint the outward effects of death³⁸, the decay of the faculties with age, and the madness that overtakes the mind—

the bodily waste, produced by long-continuous speaking—

the reflex action of the senses, produced by the nervous strain of witnessing games and spectacles for many days in succession; the insensibility to the pain of the severest wounds in the excitement of battle! In his account of the plague of Athens, in which he enters into much greater detail than Thucydides, he displays the minute observation of a physician, as well as the profound thought of a moralist.

The 'vivida vis' of his understanding is apparent also in the clearness and consecutiveness of his philosophical style. His complaint of 'the poverty of his native tongue' is directed against the capacities of the Latin language for scientific, not for poetical expression—

That language, which gives admirable expression to the dictates of common sense and to the dignified emotions which inspire the conduct of great affairs, is ill adapted both for the expression of abstract ideas and for maintaining a long process of connected argument. Lucretius has occasionally to meet the first difficulty by the adoption of Graecisms, and the second by some sacrifice of artistic elegance. Thus he uses omne for τὸ πᾶν (II. 1108), esse, again, for τὸ εἶναι, and the like. Something of a formal and technical character appears in the links by which his argument is kept together, as in the constantly recurring use of certain connecting particles, such as the 'etenim,' 'quippe ubi,' 'quod genus,' 'amplius hoc,' 'huc accedit,' and the like. Virgil has retained some of the most striking of these connecting formulae, such as 'contemplator item,' 'nonne vides,' etc.; but, as was natural in a poem setting forth precepts and not proofs, he uses them much more sparingly and with more careful selection. As used by Lucretius, they add to our sense of the vividness of the book, of the constant personal address of the author, and of his ardent polemical tone. They also keep the framework of the argument more compact and distinct: but they bring into greater prominence the artistic mistake of conducting an abstract discussion in verse. The very merits of the work considered as an argument,—its clearness, fullness, and consecutiveness,—detract from the pleasure which a work of art naturally produces. But the style cannot be too highly praised for its logical coherence and lucid illustration. The meaning of Lucretius can never be mistaken from any ambiguity in his language. There are difficulties arising from the uncertainty of the text, difficulties also from our unfamiliarity with his method and principles, or with the objects he describes, but none from confusion in his ideas or his reasoning, or from a vague or unreal use of words.

II.—The Speculative Ideas in Lucretius.

But it is in his grasp of speculative ideas, and in his application of them to interpret the living world, that the greatness of Lucretius as an imaginative thinker is most apparent. The substantial truth of all the ancient philosophies lay in the ideas which they attempted to express and embody, not in the symbols by which these ideas were successively represented. Lucretius has a place among the few adventurous thinkers of antiquity who attained to high eminences of contemplation, which were hidden from the mass of their contemporaries, and which, in the breadth of view afforded by them, are not far below the higher levels of our modern conceptions of Nature and human life. And there came to him, as to the earlier race of thinkers, that which comes so rarely to modern enquiry, the fresh and poetical sense of surprise and keen curiosity, as at the first discovery of a new country, or the first unfolding of some illimitable prospect.

(1)  In the philosophy of Lucretius the world is conceived as absolutely under the government of law. The starting-point of his system—

is an inference from the recognition of this condition. There is no need to prove its truth: it is openly revealed in all the processes of Nature. This fact of universal order is indeed supposed to result from the eternal and immutable properties of the atoms and from the original limitation in their varieties: but the idea of law is prior to, and the condition of, all the principles enunciated in the first two books, in regard to the nature and properties of matter. In no ancient writer do we find the certainty and universality of law more emphatically and unmistakably expressed than in Lucretius. This is the final appeal in all controversy. The superiority of Epicurus is proclaimed on the ground of his having discovered the fixed and certain limitations of all existence—

Following on his steps the poet himself professes to teach—

In another place he says—

All knowledge and speculative confidence are declared to rest on this truth—

Superstition, the great enemy of truth, is said to be the result of ignorance of 'what may be and what may not be.' This is the thought which underlies and gives cogency to the whole argument. The subject of the poem is 'maiestas cognita rerum,'—the revelation of the majesty and order of the universe. The doctrine proclaimed by Lucretius was, that creation was no result of a capricious or benevolent exercise of power, but of certain processes extending through infinite time, by means of which the atoms have at length been able to combine and work together in accordance with their ultimate conditions. The conception of these ultimate conditions and of their relations to one another involves some more vital agency than that of blind chance or an iron fatalism⁴⁶. The 'foedera naturai' are opposed to the 'foedera fati.' The idea of law in Nature, as understood by Lucretius, is not, necessarily, inconsistent with that of a creative will determining the original conditions of the elemental substances. Though the ultimate principles of Lucretius are incompatible with a belief in the popular religions of antiquity, his mode of conceiving the operation of law in the universe is not irreconcileable with the conceptions of modern Theism.

The idea of law not only supports the whole fabric of his physical philosophy, but moulds his convictions on human life and imparts to his poetry that contemplative elevation by which it is pervaded. It is from this ground that he makes his most powerful assault on the strongholds of superstition. Nature is thus declared to be free from the arbitrary and capricious agency of the gods:—

Man also is under the same law, and is made free by his knowledge and acceptance of this condition. A sense of security is thus gained for human life; a sense of elevation above its weakness and passions, and the courage to bear its inevitable evils⁴⁸. This absolute reliance on law does not act upon his mind with the depressing influence of fatalism. Although the fortunes of life and the phases of individual character are said to be the results of the infinite combinations of blind atoms, yet man is made free by knowledge and the use of his reason. Notwithstanding the original constitution of his nature, arising out of influences over which there is no control, he still has it in his power to live a life worthy of the gods:—

From these high places of his philosophy,—'the "templa serena" well-bulwarked by the learning of the wise'⁵⁰ he derives not only a sense of certainty in thought and security in life, but also his wide contemplative view, and his profound feeling of the majesty of the universe. The idea of universal law enables him to apprehend in all the processes of Nature a presence which awakens reverence and enforces obedience. This idea imparts unity of tone to the whole poem, informs its language, and seems to mould the very rhythm of its verse.

(2)  But a closer view brings another aspect of the world into light; viz. the interdependence of all things on one another. There is not only fixed order, but there is also infinite mobility in Nature. The sum of all things remains unchanged, though all individual existences decay and perish. So too the sum of force remains the same⁵¹. There is no rest anywhere; all things are continually changing and passing into one another; decay and renovation form the very life and being of all things. Nothing is ever lost. 'Nature repairs one thing from another, and allows of no birth except through the death of something else':—

As the 'ever-during peace' at the heart of all things is supposed to result from the eternal and immutable properties of the atoms, this 'endless agitation' arises out of their unceasing motion through infinite space. There are two kinds of motion,—the one tending to the renewal,—the other, to the destruction of things as they now exist. The maintenance of our whole system depends on the equilibrium of these opposing forces—

There is thus seen to be not only absolute order, but also infinite change in the processes of Nature. Decay and renovation, death and life, support the existing creation in unceasing harmony. The imagination represents this process under the impressive symbol of an endless battle, in which now one side now the other gains some position, but neither, as yet, can become master of the field—

This symbol is the poetical form of the old philosophical distinction of αὔξησις and φθορά. It is another form of the ἔρις and φιλία which to the imagination of Empedocles appeared to pervade the universe. The idea of a constant battle imparts to the infinite and all-pervading movement of Nature the interest and the life of human passion on the grandest and widest sphere of action. The greatness of the thought makes each particular object in Nature pregnant with a deeper meaning, associates trivial and ordinary phenomena with a sense of imaginative wonder, and throws an august solemnity around the familiar aspects of human life. The passage in which this principle is most powerfully announced at ii. 575, etc., swells into deeper and grander tones, as the real human pathos involved in this strife of elements is made manifest. This struggle of life and decay is no mere war of abstractions: it is the daily and hourly process of existence. Birth and death are the fulfilment of this law. 'The old order changeth, yielding place to new'—