Pluralism, in philosophy, theory that considers the universe explicable in terms of many principles or composed of many ultimate substances. It describes no particular system and may be embodi...

Earth, in chemistry, metallic oxide not readily reducible by chemical means, e.g., alkaline earths, rare earths, and alumina. The name is also applied to certain absorbent clays, e.g., fuller'...

Anaxagoras, c.500–428 B.C., Greek philosopher of Clazomenae. He is credited with having transferred the seat of philosophy to Athens. He was closely associated with many famous Athenians and i...

Democritus, c.460–c.370 B.C., Greek philosopher of Abdera; pupil of Leucippus. His theory of the nature of the physical world was the most radical and scientific attempted up to his time. He a...

Forster, E. M. (Edward Morgan Forster), 1879–1970, English author, one of the most important British novelists of the 20th cent. After graduating from Cambridge, Forster lived in Italy and Gre...

Arnold, Matthew, 1822–88, English poet and critic, son of the educator Dr. Thomas Arnold.Arnold was educated at Rugby; graduated from Balliol College, Oxford in 1844; and was a fellow of Oriel...

Transmigration of souls or metempsychosis [Gr.,=change of soul], a belief common to many cultures, in which the soul passes from one body to another, either human, animal, or inanimate. The Au...

Matter, anything that has mass and occupies space. Matter is sometimes called koinomatter (Gr. koinos=common) to distinguish it from antimatter, or matter composed of antiparticles. The genera...

Evolution, concept that embodies the belief that existing animals and plants developed by a process of gradual, continuous change from previously existing forms. This theory, also known as des...

Medicine, the science and art of treating and preventing disease. Prehistoric skulls found in Europe and South America indicate that Neolithic man was already able to trephine, or remove disk...