ZENKER, tsen'kr, FRIEDRICH ALBERT VON (1825-98). A German physician, celebrated for his discovery of triehiniasis. He was horn in Dresden, and was educated in Leipzig and Heidelberg. Attached to the city hospital of Dresden in 1S51, lie added, in 1855. the duties of professor of pathological anatomy and gen eral pathology in the surgico-medical academy of that city. In 1862 he became professor of pathological anatomy and pharmacology at Er langen. Three years afterwards lie assumed with Ziemssen the editorship of the Deutsches Archie [en klinischc .1Irdizin. In 1805 he re tired from active service. His important discov ery of the danger of trichina) dates from 1860. In that year he published /' ebcr die Trichincu kra»khcit des .11riischc-n (in vol. XViii. of Vir chow's rch . 'Ibis was followed by Beitnige an nornialc» mind pathologischen Anatomic dcr Lunge ( 1862 ) ; Cube). Stanbinhalatlonshrank bel1e), der L11179'01 (1860) ; Die Krankheiten dcs Oesophagus (in vol. vii. of Ziemssen's Handbuch der speziell-n Pathologic and Thcrapic, 1877).
ZE'NO (Lat.. from Gk. Z MI5 I1) (C ARS ? Eleatic philosopher, horn at Elea I Vella ), a town of Luennia in Southern Italy. Ile was a favorite pupil of Parmenides. At the age of forty lie accompanied his master to Athens, where he resided some lime and numbered among his pupils Pericles and Callias. Tradition says that after his return to Elea he joined a MONT fiPDI to deliver the city from the tyrant Near elms, and when the attempt failed, he was cap tured and put to torture. Of this, however, the evidenee is not satisfactory. As a follower of Pant elides lie snpported his doctrines by in direct demonstration, in which he attempted to point out that belief in the real existence of changing phenomena led to contradiction. Ile tried to establish the truth of the unity of being by showing that the hypotheses of motion, mul tiplicity, and sense have inherent contradictions. To the real existence of motion lie objected that motion cannot begin, because the moving body cannot arrive at any place from that in which it is until it has passed through the unlimited number of intermediate spaces. Nov, as it is at any given moment in a particular place, it can not leave that position, therefore the flying arrow is in reality at rest. His second argument was the famous proof that Achilles cannot overtake the tortoise because at any moment lie only reaches the place previously left by the tortoise; his other arguments are similar. He likewise argued against the reality of space, for, if all that exists were in a given space, that space itself would be included in another space, and so on without limit. Against sense perception he said that if a measure of grain in falling pro duced a sound, every single grain and smallest fraction thereof must produce a sound: but if the latter be not true, then the whole measure, whose effect can be nothing but the sum of the effects produced by its parts, can produce no sound. Zeno's arguments against the reality of
motion were answered by Aristotle in his Physics, but the argument still had considerable influence on the development of metaphysics in the latter period. Consult: Ritter and Preller, llistoria Philosophiw Grayer (8th ed., Gotha, 1898) ; Zel ler, Philosophic dcr Griechcn (4th ed., vol. i., Leipzig, 1900) ; also, Zeller's Prc-Socratic Phi losophy, vol. i. (New York, 1881) ; Ueberweg, History of Philosophy, vol. i. (New York, 1887).
ZENO (4th and early 3d century rf.c.). The founder of Stoic philosophy, born at Citium, in the island of Cyprus. The exact date of his birth is unknown, as is that of his death, but lie is said to have lived to a great age. He was the son of a merchant. and was himself engaged in trade during the earlier part of his life, hut according to tradition a shipwreck caused him to reside for a time at Athens, where the works written by the disciples of Socrates in regard to their master filled hint with admiration, and lie joined himself as pupil to Crates the Cynic. Ifis earliest writings according to tradition contained much that savored of the harshness and blunt ness of the Cynic doctrine. Failing to find slat eient satisfaction from Cynic philosophy, he turned to the Alegarian Still)°, from whom lie learned the art of disputation, and later to Xenovrates and Polemo of the Academy. Not long after 310 he founded his own school in the Painted Porch where. accord ing in Apollonius, lie taught for fifty-eight years. Diogenes Laert ins mentions a number of works by Idin, no one of which has been preserved. Tic and his followers strove to realize the virtuous wise man for whom the idealized Socrates was a model. The ethics of the school, which were strongly inilueneed by Cynicism, were most pro ductive in that they discriminated carefully be tween what was simply right and goof and what was Tlelr physics were strongly in fluenced by Pythagoras and TTeraclitus. The Athenians held Zeno in great regard during his life, and after his death honored him with a tomb built at public expense and a bronze D101111 DICIlt because of the temperance and virtue which he had shown in his own life as well as teach ings. Consult: Ritter and Preller, istoria Philosophic! Grwea' (8th ed., Gotha, 1898) ; Philosophic der Geicchen, vol. iii. (3d ed., Leipzig, 1880) ; Zeller, ,Stoics, Epicureans, and Sceptics (London, 1870) ; Ueberweg, History of Philosophy, Eng. trans. (New York, 1887) ; and Waelismuth, Dc Zcnove ct Cleanthc (G6ttingen, 1874).