Epicureanism on the other hand by employing the theory of evolution was able to unite man and nature once more. And since man is so self-centered that his imagination refuses to extend sympathetic treatment to nature unless he can feel a vital bond of fellowship with it, the poetry of romance became possible only upon the discovery of that unity. This is doubtless why Lucretius, first of all the Romans, could in his prooemium bring back to nature that sensuousness which through the songs of the troubadours has become the central theme of romantic poetry even to our day.
Nam simulac species patefactast verna diei …
Aëriae primum volucres te diva tuumque
Significant initum perculsae corda tua vi,
Inde ferae pecudes persultant pabula laeta.
Vergil, convinced by the same philosophy, expresses himself similarly:
Et genus aequoreum, pecudes, pictaeque volucres amor omnibus idem.
And again:
Avia tum resonant avibus virgulta canoris
Et Venerem certis repetunt armenta diebus
Parturit almus ager Zepherique trementibus auris
Laxant arva sinus.
It is, of course, the theme of "Sumer is icumen in." Lucretius feels so strongly the unity of naturally evolved creation that he never hesitates to compare men of various temperaments with animals of sundry natures—the fiery lion, the cool-tempered ox—and explain the differences in both by the same preponderance of some peculiar kind of "soul-atoms."
Obviously this was a system which, by enlarging man's mental horizon and sympathies, could create new values for aesthetic use. Like the crude evolutionistic hypotheses in Rousseau's day, it gave one a more soundly based sympathy for one's fellows—since evolution was not yet "red in tooth and claw." If nature was to be trusted, why not man's nature? Why curse the body, any man's body, as the root-ground of sin? Were not the instincts a part of man? Might not the scientific view prove that the passions so far from being diseases, conditioned the very life and survival of the race? Perhaps the evils of excess, called sin, were after all due to defects in social and political institutions that had applied incorrect regulative principles, or to the selfishly imposed religious fears which had driven the healthy instincts into tantrums. Rid man of these erroneous fears and of a political system begot for purposes of exploitation and see whether by returning to an age of primitive innocence he cannot prove that nature is trustworthy.[2]
[Footnote 2: Lucretius, III, 37-93; II, 23-39; V, 1105-1135.]
There is in this philosophy then a basis for a large humanitarianism, dangerous perhaps in its implications. And yet it could hardly have been more perilous than the Roman orthodox religion which insisted only upon formal correctness, seldom upon ethical decorum, or than Stoicism with its categorical imperative, which could restrain only those who were already convinced. The Stoic pretence of appealing to a natural law could be proved illogical at first examination, when driven to admit that "nature" must be explained by a question-begging definition before its rule could be applied.