IDEA, a mental image, form, or repre sentation of anything. The word idea has been taken in very many and very_ different senses, the history of which would be a history of philosophy. Aris totle (384-322 B. c.) taught that though the One, apart from and beside the many, does not exist, none the less must a unity be assumed as (objectively) present in the many; and the Stoics (Zeno, 355-263 B. c.) maintained the doc trines of subjective concepts formed through abstraction. According to Plu tarch of Chmronea (toward the end of the 1st century), the ideas were inter mediate between God and the world; they 1.vere the pattern and God the ef ficient cause. For Plotinus (203-270) the primordial essence was elevated above the Platonic ideas, which were emanations from the One. St. Thomas of Aquin (1227-1274) recognizes a form in which the universal exists before things—viz., as ideas in the divine mind. For Descartes (1596-1650), "ideas are the forms of things received into the soul"; for Spinoza (1632-1677) the "con cepts formed by the mind as a thinking thing"; and Locke (1632-1704) says, " whatsoever the mind perceives in itself, or is the immediate object of perception, thought, or understanding, that I call an idea." In the philosophy of Leibnitz
(1646-1716) ideas are the active forces of his monads; Berkeley (1684-1753) used the word as equivalent to phenome non; Hume (1711-1776) defines ideas as "copies of perceptions," and Condillac (1715-1780) as "mental representations of objects of apprehension." Kant (1724-1804) gives the name of ideas to those "necessary conceptions of the rea son for which no corresponding real ob jects can be given in the sphere of the senses." According to Erasmus Darwin (1731-1802), an idea is a "contraction, or motion, or configuration of the fibers which constitute the immediate organs of sense." James Mill (1773-1836) calls ideas "what remain after sensation has gone," and Herbart (1776-1841) "typi cal conceptions." Schopenhauer (1788 1860) posits as intermediate between the universal will and the individual in which it appears, various ideas as real species forming stages in the objectifica tion of the will.