The light and heat of the central fire he believed that we received through the sun, which he considered a kind of lens: and perfection, he conceived to exist in direct ratio to the distance from the central fire. The universe, itself, they looked upon as having subsisted from all eternity, controlled by an eternal supreme Deity; who established both limits and infinity; and whom they often speak of as the absolute μονὰς, or unity. He pervaded (though he was distinct from) and presided over the universe. Sometimes, too, he is called the absolute _Good_,—while the origin of evil is attributed not to him, but to matter which prevented him from conducting everything to the best end. With respect to man, the doctrine of Pythagoras was that known by the name of the Metempsychosis,—that the soul after death rested a certain time till it was purified, and had acquired a forgetfulness of what had previously happened to it; and then reanimated some other body. The ethics of the Pythagoreans consisted more in ascetic practice and maxims for the restraint of the passions, than in any scientific theories. Wisdom they considered as superior to virtue, as being connected with the contemplation of the upper and purer regions, while virtue was conversant only with the sublunary part of the world. Happiness, they thought, consisted in the science of the perfection of the soul; or in the perfect science of numbers; and the main object of all the endeavours of man was to be, to resemble the Deity as far as possible. _Alcmæon_ of Crotona was a pupil of Pythagoras; but that is all that is known of his history. He was a great natural philosopher; and is said to have been the first who introduced the practice of dissection. He is said, also, to have been the first who wrote on natural philosophy. Aristotle, however, distinguishes between the principles of Alcmæon and Pythagoras, though without explaining in what the difference consisted. He asserted the immortality of the soul, and said that it partook of the divine nature, because, like the heavenly bodies themselves, it contained in itself the principle of motion. _Xenophanes_, the founder of the Eleatic school, was a native of Colophon; and flourished probably about the time of Pisistratus. Being banished from his own country, he fled to the Ionian colonies in Sicily, and at last settled in Elea, or Velia. His writings were chiefly poetical. He was universally regarded by the ancients as the originator of the doctrine of the oneness of the universe: he also maintained, it is said, the unity of the Deity; and also his immortality and eternity; denounced the transference of him into human form; and reproached Homer and Hesiod for attributing to him human weaknesses. He represented him as endowed with unwearied activity, and as the animating power of the universe.