PYROXYLINE, an explosive substance obtained by steeping vegetable fibre in nitro-sulphuric acid and drying after it is washed.

PYRRHA, in Greek mythology the wife of DEUCALION (q. v.).

PYRRHIC DANCE, the chief war-dance of the Greeks, of quick, light movement to the music of flutes; was of Cretan or Spartan origin.  It was subsequently danced for display by the Athenian youths and by women to entertain company, and in the Roman empire was a favourite item in the public games.

PYRRHO, the father of the Greek sceptics, born in Elis, a contemporary of Aristotle; his doctrine was, that as we cannot know things as they are, only as they seem to be, we must be content to suspend our judgment on such matters and maintain a perfect imperturbability of soul if we would live to any good.

PYRRHONISM, philosophic scepticism.  See PYRRHO.

PYRRHUS, king of Epirus, and kinsman of Alexander the Great; essayed to emulate the Macedonian by conquering the western World, and in 280 B.C. invaded Italy with a huge army, directed to assist the Italian Greeks against Rome; in the decisive battles of that year and the next, he won “Pyrrhic victories” over the Romans, losing so many men that he could not pursue his advantage; 278 to 276 he spent helping the Greek colonies in Sicily against Carthage; his success was not uniform, and a Carthaginian fleet inflicted a serious defeat on his fleet returning to Italy; in 274 he was thoroughly vanquished by the Romans, and retired to Epirus; subsequent wars against Sparta and Argos were marked by disaster; in the latter he was killed by a tile thrown by a woman (318-272 B.C.).

PYRRHUS, called also NEOPTOLEMUS, son of Achilles; was one of the heroes concealed in the wooden horse by means of which Troy was entered, slew Priam by the altar of Zeus, and sacrificed Polyxena to the manes of his father.  Andromache, the widow of Hector, fell to him on the division of the captives after the fall of Troy, and became his wife.

PYTHAGORAS, a celebrated Greek philosopher and founder of a school named after him Pythagoreans, born at Samos, and who seems to have flourished between 540 and 500 B.C.; after travels in many lands settled at Crotona in Magna Graecia, where he founded a fraternity, the members of which bound themselves in closest ties of friendship to purity of life and to active co-operation in disseminating and encouraging a kindred spirit in the community around them, the final aim of it being the establishment of a model social organisation.  He left no writings behind him, and we know of his philosophy chiefly from the philosophy of his disciples.