Lives and Opinions of Eminent Philosophers

​Pythagoras devoted himself especially to the arithmetical aspect of geometry, and he discovered the monochord rule. Nor did he neglect medicine. Apollodorus the calculator says that he sacrificed a hecatomb when he discovered that the hypotenuse of a right-angled triangle has a square equal to the sum of the squares on the sides containing the right angle. And there is an epigram that runs thus: "When Pythagoras found that famous figure, for which he offered a glorious cattle-sacrifice." It is also said that he was the first to train athletes on meat, and Eurymenes first of all, as Favorinus says in the third book of his Memorabilia, whereas previously they used to exercise their bodies on dried figs and soft cheeses, and even wheat, as the same Favorinus says in the eighth book of his Miscellaneous History.

​Others, however, say that a certain Pythagoras, a trainer, fed them in this way, and not this philosopher. For this man even forbade the killing of animals, let alone tasting them, since they share with us the common right of a soul. And this was the pretext; but the truth was that he forbade touching living beings while training and habituating men to ease of life, so that their food might be easy to procure, by eating uncooked food and drinking simple water; for from this both health of body and sharpness of soul are produced. Indeed, he worshipped only the altar of Apollo the Father at Delos, which is behind the Horned Altar, because wheat, barley, and cakes alone were placed upon it without fire, and no victim at all, as Aristotle says in his Constitution of Delos.

​They also say that he was the first to declare that the soul, passing through a cycle of necessity, is bound at different times to different living beings; and that he was the first to introduce weights and measures among the Greeks, as Aristoxenus the musician says; and the first to say that Hesperus and Phosphorus are the same, as Parmenides says. He was so greatly admired that people used to call his disciples prophets of the voice of God; moreover, he himself says in his writing that after two hundred and seven years he had come back from Hades to mankind. Therefore, people attached themselves to him, and for the sake of his teachings Lucanians, Peucetians, Messapians, and Romans came to him.

​Down to the time of Philolaus it was not possible to know any Pythagorean doctrine; but he alone published those famous three books, which Plato wrote instructions to purchase for a hundred minae. And no fewer than six hundred used to attend his nightly lectures; and if any were deemed worthy to see him, they would write to their relatives as having attained some great thing. The Metapontines, indeed, called his house the temple of Demeter, and the alleyway a shrine of the Muses, as Favorinus says in his Miscellaneous History; and the other Pythagoreans also used to say that not all things are to be spoken to all people, as Aristoxenus says in the tenth book of his Educational Laws.

​There it is said that Xenophilus the Pythagorean, when asked how one might best educate his son, replied, "If he should become a member of a well-governed city." He also turned out many other noble and good men throughout Italy, including the lawgivers Zaleucus and Charondas; for he was skillful in creating friendship in general, and especially if he learned that someone shared in his symbols, he would immediately make him a companion and attach him as a friend.

​His symbols were the following: Do not poke the fire with a knife. Do not step over a balance. Do not sit upon a choenix. Do not eat heart. Do not help take down a burden, but help put it on. Keep bed-coverings always rolled up. Do not wear the image of a god in a ring. Obliterate the mark of a pot in the ashes. Do not wipe a seat with a torch. Do not urinate facing the sun. Do not walk on the highways. Do not offer the right hand lightly. Do not have swallows share your roof. Do not breed birds with hooked talons. Do not urinate upon or step on nail-parings and hair-cuttings. Turn away a sharp knife. When travelling abroad, do not turn back at the borders.