The founder of the healing art amongst the Greeks and Hellenic peoples generally was Pythagoras. He was imbued with Eastern mysticism, teaching that the air is full of spiritual beings, who send dreams to men and cause to men and cattle disease and health. He taught that these spirits must be conciliated by lustrations and invocations. Pliny says[360] that he taught that holding dill (_anethum_) in the hand is good against epilepsy. The health of the body is to be maintained by diet and gymnastics. It is interesting to find that this great philosopher recommended music to restore the harmony of the spirits. Besides the magic virtues of the dill, he held that many other plants possessed them, such as the cabbage (a food in great favour with the Pythagoreans), the squill, and anise. He held that surgery was not to be practised, as it is unlawful, but salves and poultices were to be permitted. His disciples attributed the union between medicine and philosophy to him. The Pythagorean philosophy turns upon the idea of numbers and the mathematical relations of things. “All things are number;” “number is the essence of everything.” The world subsists by the principle of ordered numbers. The spheres revolve harmoniously; the seven planets are the seven golden chords of the heavenly heptachord. As a corollary to this notion we have the theory of opposites. We have the odd and even, and their combinations. The even is the unlimited, the odd the limited; so all things are derived from the combination of the limited and the unlimited. Then we get the limited and the unlimited, the odd and the even, the one and many, right and left, masculine and feminine, rest and motion, straight and crooked, light and darkness, good and evil, square and oblong. When opposites unite, there is harmony. The number ten comprehends all other numbers in itself; four was held in great respect, because it is the first square number and the potential decade (1 + 2 + 3 + 4 = 10). Pythagoras was the discoverer of the holy τετρακτύς, “the fountain and root of ever-living nature.” Five signifies marriage, one is reason because unchangeable, two is opinion, seven is called παρθένος and Ἀθήνη, because within the decade it has neither factors nor product.[361]