I. A Grecian philosopher, born at Miletus, flourished in the latter half of the 6th century 13. 0. He taught that the essence of all things is air, whence all things are produced by condensation and rarefaction through eternally existing motion; that the sun and moon are fiery bodies of a flat, circular form; that the stars are also fiery substances, fastened like nails in a crystalline sphere; and that the earth is a tablet resting on air.

II. A native of Lampsacus, a historian and rhetorician, and one of the preceptors of Alexander the Great. He wrote a history of Alexander's reign, and that of his father Philip, and also a history of Greece.