There is a second species of poetry to which the name of philosophical may be given, though it better deserves that of mystical. Pantheism occupies a middle place between a scientific theory of the universe and a form of religious enthusiasm. It supplies an element in which the poetic faculty can move with freedom: for its conclusions, in so far as they pretend to philosophy, are large and general, and the emotions which it excites are co-extensive with the world. Therefore, Pantheistic mysticism, from the Bhagavadgita of the far East, through the Persian Soofis, down to the poets of our own century, Goethe, and Shelley, and Wordsworth, and Whitman, and many more whom it would be tedious to enumerate, has generated a whole tribe of philosophic singers.
Yet a third class may be mentioned. Here we have to deal with what are called didactic poems. These, like the metaphysical epic, began to flourish in early Greece at the moment when exact thought was dividing itself laboriously from myths and fancies. Hesiod with his poem on the life of man leads the way; and the writers of moral sentences in elegiac verse, among whom Solon and Theognis occupy the first place, follow. Latin literature contributes highly artificial specimens of this kind in the 'Georgics' of Virgil, the stoical diatribes of Persius, and the 'Ars Poetica' of Horace. Didactic verse had a special charm for the genius of the Latin race. The name of such poems in the Italian literature of the Renaissance is legion. The French delighted in the same style under the same influences; nor can we fail to attribute the 'Essay on Man' and the 'Essay on Criticism' of our own Pope to a similar revival in England of Latin forms of art. The taste for didactic verse has declined. Yet in its stead another sort of philosophical poetry has grown up in this century, which, for the want of a better term, may be called psychological. It deserves this title, inasmuch as the motive-interest of the art in question is less the passion or the action of humanity than the analysis of the same. The 'Faust' of Goethe, the 'Prelude' and 'Excursion' of Wordsworth, Browning's 'Sordello' and Mrs. Browning's 'Aurora Leigh,' together with the 'Musings' of Coleridge and the 'In Memoriam' of Tennyson, may be roughly reckoned in this class. It will be noticed that nothing has been said about professedly religious poetry, much of which attaches itself to mysticism, while some, like the 'Divine Comedy' of Dante, is philosophic in the truest sense of the word.
Where, then, are we to place Lucretius? He was a Roman, imbued with the didactic predilections of the Latin race; and the didactic quality of the 'De Rerum Naturâ' is unmistakable. Yet it would be uncritical to place this poem in the class which derives from Hesiod. It belongs really to the succession of Xenophanes, Parmenides, and Empedocles. As such it was an anachronism. The specific moment in the development of thought at which the Parmenidean Epic was natural has been already described. The Romans of the age of Lucretius had advanced far beyond it. The idealistic metaphysics of the Socratic school, the positive ethics of the Stoics, and the profound materialism of Epicurus, had accustomed the mind to habits of exact and subtle thinking, prolonged from generation to generation upon the same lines of speculative inquiry. Philosophy expressed in verse was out of date. Moreover, the very myths had been rationalised. Euhemerus had even been translated into Latin by Ennius, and his prosaic explanations of Greek legend had found acceptance with the essentially positive Roman intellect. Lucretius himself, it may be said in passing, thought it worth while to offer a philosophical explanation of the Greek mythology. The Cybele of the poets is shown in one of his sublimest passages (ii. 600-645) to be Earth. To call the sea Neptune, corn Ceres, and wine Bacchus, seems to him a simple folly (ii. 652-657). We have already seen how he reduces the fiends and spectres of the Greek Hades to facts of moral subjectivity (iii. 978-1023). In another place he attacks the worship of Phoebus and the stars (v. 110); in yet another he upsets the belief in the Centaurs, Scylla, and Chimæra (v. 877-924) with a gravity which is almost comic. Such arguments formed a necessary element in his polemic against foul religion (foeda religio—turpis religio); to deliver men from which (i. 62-112), by establishing firmly in their minds the conviction that the gods exist far away from this world in unconcerned tranquillity (ii. 646), and by substituting the notion of Nature for that of deity (ii. 1090), was the object of his scientific demonstration.
Lucretius, therefore, had outgrown mythology, was hostile to religion, and burned with unsurpassable enthusiasm to indoctrinate his Roman readers with the weighty conclusions of systematised materialism. Yet he chose the vehicle of hexameter verse, and trammelled his genius with limitations which Empedocles, four hundred years before, must have found almost intolerable. It needed the most ardent intellectual passion and the loftiest inspiration to sustain on his far flight a poet who had forged a hoplite's panoply for singing robes. Both passion and inspiration were granted to Lucretius in full measure. And just as there was something contradictory between the scientific subject-matter and the poetical form of his masterpiece, so the very sources of his poetic strength were such as are usually supposed to depress the soul. His passion was for death, annihilation, godlessness. It was not the eloquence, but the force of logic in Epicurus that roused his enthusiasm:—
ergo vivida vis animi pervicit et extra
processit longe flammantia moenia mundi.
No other poet who ever lived in any age, or any shore, drew inspiration from founts more passionless and more impersonal.
The 'De Rerum Naturâ' is therefore an attempt, unique in its kind, to combine philosophical exposition and poetry in an age when the requirements of the former had already outgrown the resources of the latter. Throughout the poem we trace a discord between the matter and the form. The frost of reason and the fire of fancy war in deadly conflict; for the Lucretian system destroyed nearly everything with which the classical imagination loved to play. It was only in some high ethereal region, before the majestic thought of Death or the new Myth of Nature, that the two faculties of the poet's genius met for mutual support. Only at rare intervals did he allow himself to make artistic use of mere mythology, as in the celebrated exordium of the first book, or the description of the Seasons in the fifth book (737-745). For the most part reason and fancy worked separately: after long passages of scientific explanation, Lucretius indulged his readers with those pictures of unparalleled sublimity and grace which are the charm of the whole poem; or dropping the phraseology of atoms, void, motion, chance, he spoke at times of Nature as endowed with reason and a will (v. 186, 811, 846).
It would be beyond the scope of this essay to discuss the particular form given by Lucretius to the Democritean philosophy. He believed the universe to be composed of atoms, infinite in number, and variable, to a finite extent, in form, which drift slantingly through an infinite void. Their combinations under the conditions of what we call space and time are transitory, while they remain themselves imperishable. Consequently, as the soul itself is corporeally constituted, and as thought and sensation depend on mere material idola, men may divest themselves of any fear of the hereafter. There is no such thing as providence, nor do the gods concern themselves with the kaleidoscopic medley of atoms in transient combination which we call our world. The latter were points of supreme interest to Lucretius. He seems to have cared for the cosmology of Epicurus chiefly as it touched humanity through ethics and religion. To impartial observers, the identity or the divergence of the forms assumed by scientific hypothesis at different periods of the world's history is not a matter of much importance. Yet a peculiar interest has of late been given to the Lucretian materialism by the fact that physical speculation has returned to what is substantially the same ground. The most modern theories of evolution and of molecular structure may be stated in language which, allowing for the progress made by exact thought during the last twenty centuries, is singularly like that of Lucretius. The Roman poet knew fewer facts than are familiar to our men of science, and was far less able to analyse one puzzle into a whole group of unexplained phenomena. He had besides but a feeble grasp upon those discoveries which subserve the arts of life and practical utility. But as regards absolute knowledge—knowledge, that is to say, of what the universe really is, and of how it became what it seems to us to be—Lucretius stood at the same point of ignorance as we, after the labours of Darwin and of Spencer, of Helmholtz and of Huxley, still do. Ontological speculation is as barren now as then, and the problems of existence still remain insoluble. The chief difference indeed between him and modern investigators is that they have been lessoned by the experience of the last two thousand years to know better the depths of human ignorance, and the directions in which it is possible to sound them.
It may not be uninteresting to collect a few passages in which the Roman poet has expressed in his hexameters the lines of thought adopted by our most advanced theorists. Here is the general conception of Nature, working by her own laws toward the achievement of that result which we apprehend through the medium of the senses (ii. 1090):—