Epicurus, who lived from 341 to 270 and was one of the most prominent figures of ancient rationalism. Epicurus did not believe in anything supernatural; he maintained that everything could be explained on a purely natural and mechanical basis. He excluded teleology, the doctrine of a conscious plan or purpose in evolution and nature from any place in true philosophy, thus taking an important stand in a struggle not yet settled. Unfortunately, Epicurus did not take the trouble to explain what his postulated natural causes were, or how they behaved. The agnostic may well say, with Elliot, that the organic world seems to be teleologically organized merely because it cannot be organized otherwise, but he must stand ready to show grounds for his statement.
After Epicurus we must pass from Greece to Rome. T. Lucretius Carus (99–55), more commonly known as Lucretius, revived the teachings of ancient Greek philosophers and united them with those of Epicurus, whose doctrines he made famous in the long poem, "De Rerum Natura." Lucretius maintained a purely mechanical, rationalistic view of nature, but ignored the valuable work of Aristotle. He revived Empedocles' hypothesis of survival, but confined its application to the mythical monsters of past ages—centaurs, chimeras, and so on. He believed in the spontaneous generation of life, speaking of mounds arising, "from which people sprang forth, for they had been nourished within." "In an analogous manner,"
