Dagobert D. Runes, Dictionary of Philosophy, 1942.
Zaddik, Joseph Ibn: Judge at Cordova (1080-1149). Philosophic work written in Arabic is the Microcosm (Heb. Olam Katon). See Jewish Philosophy.
Zarathustra: A historic personality whose life became "enshrowded in legend. He lived not later than the 6th century B.C. in ancient Persia (Iran or Bactria) and is credited with establishing a dualism called after him Zoroastrianism (q.v.). In Also sprach Zarathustra, Nietzsche makes him, though dissociated from his doctrines, the bearer of his message. -- K.F.L.
Zendavesta: (from Middle Persian Zend u Avista, "commentary and text") The Commentary, still used today as sacred scripture among the Parsis (see Zoroastrianism), on the basic text which was composed by the followers of Zarathustra (q.v.), but had become unintelligible due to its archaic nature. -- K.F.L.
Zeno of Elea: (about 490-430 B.C.) Disciple of Parmenides, defended the doctrine of his master that only changeless "Being" is real by indirect proofs exposing the logical absurdities involved in the opposite view, namely that plurality and change are real. Zeno's famous arguments against the possibility of motion were intended as proofs that motion was full of contradictions and that it could not therefore serve as a principle for the explanation of all phenomena, as the atomists, Heraclitus, Empedocles and others had taught. -- M.F.
Zeno the Stoic: (c. 340-265 B.C.) A native of Cyprus and the founder of the Stoic School in Athens. His philosophy was built on the principle that reality is a rational order in which nature is controlled by laws of Reason, interpreted in the vein of pantheism. Men's lives are guided by Providence against which it is futile to resist and to which wise men willingly submit. -- R.B.W.
Zermelo, Ernst (Friedrich Ferdinand), 1871-, German mathematician. Professor of mathematics at Zurich, 1910-1916, and at Freiburg, 1926-. His important contributions to the foundations of mathematics are the Zermelo axiomatic set theory (see logic, formal, § 9), and the explicit enunciation of the axiom of choice (q.v.) and proof of its equivalence to the proposition that every class cm be well-ordered.
Zetetic: (Gr. zeteo, to seek) A procedure by inquiry. A search (in mathematics) after unknown quantities. A seeker. -- V.F.
Ziehen, Theodor: (b. 1862) A German thinker whose main interest lay in the field of physiological psychology. -- R.B.W.
Zoroastrianism: (from Zoroaster) A life-affirming Indo-Iranian religion, also known as Mazdaism, Bah Din, Parsiism, and Fire-worship, established by Zarathustra (q.v.), weakened by the conquests of Alexander the Great, resuscitated, then practically extinguished by the advance of Mohammedanism, but still living on in the Gabar communities of Persia and the Parsis of Bombay. It is ethical and dualistic in that the struggle between good and evil is projected into cosmology and symbolized by a warfare between light and darkness which is conceived on the one hand naturalistically and manifesting itself in a deification of the shining heavily bodies, veneration of fire, fear of defilement, and purificatory rites, and, on the other, mythologically as the vying for supremacy between Ormazd and Ahriman (q.v.) and their hosts of angels and demons. Man must choose between light and darkness, truth and falsehood, moral right and wrong, and thus gain either eternal bliss or agony. -- K.F.L.
Zwingliism: The theological thought of Huldreich Zwingli (1481-1531), early Protestant Reformer of Zurich, Switzerland. His theology was theocentric: God's activity is all-pervading and widely revealed. He was a student of the Greek N.T. and of humanistic subjects, a friend of Erasmus. (See Reformation). He followed Augustine's doctrine of man's original sin and sinfulness with some modifications. He anticipated Calvin's doctrine of election (see Calvinism) as an act of the Divine good and rational will, and he held the feudalistic theory of the atonement of substitution framed by Anselm. The sacraments were not mystical conveyors of divine grace to him, they were rather outward signs of an inward spiritual grace. In the famous Marburg Colloquy, he broke with Luther and his followers on the interpretation of the Lord's Supper. -- V.F.