I quite like DeWitt on this point;
That's from pages 66-67 of Epicurus and his Philosophy. Lucretius had indeed written (Book IV, line 823) that sight did not exist before the eyes, or language before the tongue; these organs were not created to fulfill a purpose. Rather, their existence afforded the opportunity to be adapted by the organism for the uses with which we now associate them.
In this way the early Epicureans prefigured Charles Darwin, who also wrote about the eye in a well-remembered passage that is often abused by creationists:
QuoteTo suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree. Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real. How a nerve comes to be sensitive to light, hardly concerns us more than how life itself first originated; but I may remark that several facts make me suspect that any sensitive nerve may be rendered sensitive to light, and likewise to those coarser vibrations of the air which produce sound.
But if Epicurus rejected the Platonic and Aristotelian view of teleology, what justification can we make for his continued use of the word telos (τέλος)? DeWitt resolves the problem by suggesting that, while Epicurus did throw out creationism and intelligent design, he did not wholly reject teleology.
Quote"This amounts to saying that a nonpurposive Nature had produced a purposive creature, for whom alone an end or goal of living could have a meaning. This is teleology at a minimum."
He enlarges on this theme with a discussion of the word nature as opposed to reason on pages 127-132, and here is a relevant excerpt:
QuoteThe priority of Nature was also insisted upon in establishing the identity of the end or telos. Aristotle had furnished a precious hint in this connection; he wrote "that perhaps even in the case of the lower animals there is some natural good superior to their scale of intelligence which aims at the corresponding good." To this principle Epicurus adapted his procedure. By the promptings of Nature alone, apart from reason, every animate thing, the moment it is born, reaches out for pleasure and shrinks from pain. Consistent with this reasoning is the steady practice of referring to pleasure as "the end of Nature," which occurs five times in our scant remains. As analogous phrases may be cited "the good of Nature" and "the pleasure of Nature," all of them implying that reason played no necessary role in establishing the truth. Similar is the implication of parallel phrases such as "the wealth of Nature," signifying that Nature and not reason reveals the true meaning of wealth; and also "the limits of Nature," implying that Nature and not reason teaches the true limits of the desires.