ABSTRACT
EARLY in the history of human speculation, the meaning of the eternal flux of things occupied the attention of philosophers, and systems of philosophy such as those of Democritus and Lucretius arose that attempted to explain phenomena by the unceasing motion of minute bodies or atoms, ever assembling, breaking up, and re-assuming innumerable forms and combinations. Sometimes emphasis was on the eternal forms of things, although the things themselves pass away, sometimes on the new things that arise in their stead, and some-times on the origin of the things that have grown or come to be. The three main meanings of evolution thus trace back to early thought; it may mean persistence despite change, it may refer to the emergence of newness or novelty, and finally it may indicate an inquiry into origins.
