Hippasus of Metapontum (/ˈhɪpəsəs/; Greek: Ἵππασος, Híppasos; fl. 5th century BC), was a Pythagorean philosopher. Little is known about his life or his beliefs, but he is sometimes credited with the discovery of the existence ofirrational numbers. The discovery of irrational numbers is said to have been shocking to the Pythagoreans, and Hippasus is supposed to have drowned at sea, apparently as a punishment from the gods, for divulging this. However, the few ancient sources which describe this story either do not mention Hippasus by name or alternatively tell that Hippasus drowned because he revealed how to construct a dodecahedron inside a sphere. The discovery of irrationality is not specifically ascribed to Hippasus by any ancient writer. Some modern scholars though have suggested that he discovered the irrationality of √2, which it is believed was discovered around the time that he lived.
Life[edit]
Little is known about the life of Hippasus. He may have lived in the late 5th century BC, about a century after the time of Pythagoras. Metapontum in Italy (Magna Graecia) is usually referred to as his birthplace,[1][2][3][4][5] although according to Iamblichus some claim Metapontum to be his birthplace, while others the nearby city of Croton.[6] Hippasus is recorded under the city of Sybaris in Iamblichus list of each city's Pythagoreans.[7] He also states that Hippasus was the founder of a sect of the Pythagoreans called the Mathematici(Greek: μαθηματικοί) in opposition to the Acusmatici (Greek: ἀκουσματικοί);[8] but elsewhere he makes him the founder of the Acusmatici in opposition to the Mathematici.[9]
Doctrines[edit]
Aristotle speaks of Hippasus as holding the element of fire to be the cause of all things;[10] and Sextus Empiricus contrasts him with the Pythagoreans in this respect, that he believed the arche to be material, whereas they thought it was incorporeal, namely, number.[11]Diogenes Laërtius tells us that Hippasus believed that "there is a definite time which the changes in the universe take to complete, and that the universe is limited and ever in motion."[2] According to one statement, Hippasus left no writings,[2] according to another he was the author of the Mystic Discourse, written to bring Pythagoras into disrepute.[12]
A scholium on Plato's Phaedo notes him as an early experimenter in music theory, claiming that he made use of bronze disks to discover the fundamental musical ratios, 4:3, 3:2, and 2:1.[13]