The practical purpose of the poem—the overthrow of superstition—limits the argument to these subjects of discussion. They are severally mentioned where the argument is resumed in Books iii, iv, v, and vi, as those matters which require a clear explanation from the poet. All the topics enunciated in the opening statement are discussed with the utmost fulness. The great strongholds of superstition are attacked and overthrown in regular succession. In the introduction to the sixth book, the lines (91-95)
Tu mihi supremae praescribta ad candida calcis, etc.
clearly show that the poet considered himself approaching the end of his task.
But, on the other hand, an examination of the poem in detail leads to the conclusion that it did not receive its author's final touch. The continuity of the argument is occasionally broken in all the books except the first. In the fourth, fifth, and sixth, especially, these breaks are very frequent, and there are more frequent instances in them of repetition and careless workmanship. They extend also to a greater length than the earlier books, which would naturally be the case if they had not received the author's final revision. The poem throughout gives the impression of great fulness of matter—
Usque adeo largos haustus e fontibu' magnis
Lingua meo suavis diti de pectore fundet;—
and in the composition of these later books, new suggestions seem to have been constantly occurring to the poet as new materials were added to his stores of knowledge: and the first draft of his argument has not been recast so as to incorporate and harmonise them with it. The passages containing these new materials appear to have been fitted into the place which they now occupy in the work, not always very judiciously, either by Cicero or some other editor.
It was also part of the author's design to enunciate his deepest thoughts on the Gods, on Nature, and on human life in more highly finished digressions from the main argument. Such passages are, in general, introduced at the beginning and the end of the different books. They seem to bring out the more catholic interest which underlies the special subject of the poem. Some of these passages are highly finished, and were evidently fixed by the poet in the places which he designed them to occupy. Such are, especially, the introductions to the first, second, and third books, and the concluding passages of the second and third. But the repetition of a passage of the first book as the introduction to the fourth, the long break in the continuity of the introduction to the fifth, the unfinished style of that to the sixth, and the abrupt and episodical conclusion to the whole poem (when contrasted with its elaborately artistic introduction), show that the same cause which marred the symmetry of his argument deprived it of the finished execution of a work of art. Yet these books—especially the fifth—are as rich in poetical feeling and substance as the earlier ones. The eye and hand of the master are as powerful as in the first enthusiasm with which he dedicated himself to his task, but they are less certain in their action. Whether his powers became intermittent owing to the attacks of illness, or whether his habit was to work roughly in the first instance and to perfect his work by subsequent revision, which in the case of his latest labours was prevented by death, must remain uncertain. It is a noticeable result of the vastness of the tasks which Roman genius set before itself, that two such works as the didactic poem of Lucretius and the Aeneid of Virgil were left unfinished by their authors, and given to the world in a more or less imperfect condition by other hands.
The poem, though incomplete in regard to the arrangement of its materials and artistic finish, presents a full and clear view of the philosophy accepted and expounded by Lucretius. What, then, is the intellectual interest and value of the work, considered as a great argument, in which the plan of Nature is explained, and the position of man in relation to that plan is determined? Is it true, as an illustrious modern critic[17] has said, that 'the greatest didactic poem in any language was written in defence of the silliest and meanest of all systems of natural and moral philosophy'? Is this work a mere maze of ingeniously woven error, enriched with a few brilliant colours which have not yet faded with the lapse of time? or is it a great monument of the ancient mind, marking indeed its limitations, but at the same time perpetuating the memory of its native strength and energy? Has all the meaning of this controversy between science in its infancy and the pagan mythology in its decrepitude passed away, as from the vantage-ground of nineteen centuries the blindness and the ignorance of both combatants are apparent? Or, may we not rather discern that amid all the confusion of this dim νυκτομαχία a great cause was at issue; that truths the most vital to human wellbeing were involved on both sides; and that some positions were then gained which are not now abandoned?
In estimating the strength and the weakness of the system expounded by Lucretius, it is necessary to distinguish between the exposition of the principles of the atomic philosophy, contained in the first two books, and the explanation of natural phenomena contained in the remaining books. The first, notwithstanding some arbitrary and unverifiable assumptions, represents a real and important stage in the progress of enquiry; the second, although containing many striking observations and immediate inferences from the facts and processes of Nature, is, from the point of view of modern science, to be regarded mainly, as a curious page in the records of human error. Whatever may be said of the Epicurean additions to the system, it seems to be admitted that the original hypothesis of Democritus has been more pregnant in results, and has more affinity with the most advanced physical speculations of modern times, than the doctrines of all the other philosophers of antiquity. But even amid the mass of unwarranted assumptions and erroneous explanations contained in the later books, the topics discussed—such as the relation of the mind to the body, the mode by which sensible impressions are conveyed to the mind, the processes by which our globe assumed its present form, the origin of life, the evolution of humanity from its lowest to its higher stages of development, the origin of spiritual beliefs, of the humaner sentiments, of language, etc.—possess the interest of being kindred to those on which speculative activity is most employed in the present day. If the study of Lucretius forces upon our minds the arbitrary assumptions, the inadequate method, and the false conclusions of ancient science, it enables us to appreciate the disinterested greatness of its aims, and the enlightened curiosity which sought to solve the vastest problems.