It is difficult to grasp this point, Lucretius acknowledged, but “what has been created gives rise to its own function.” (4.835) That is, he explained, “Sight did not exist before the birth of the eyes, nor speech before the creation of the tongue.” (4.836–37) These organs were not created in order to fulfill a purposed end; their usefulness gradually enabled the creatures in whom they emerged to survive and to reproduce their kind.
