Theophrastus, naturalist and philosopher, born at Eresos, in the island of Lesbos, probably 373 or 368 B.C., repaired, after an excellent education, to Athens, where he heard Plato and Aristotle, attaching himself particularly to the latter, whose intimate friend and successor he became. He accompanied his master to Stagira, and inherited, by will, the whole Aristotelian library, the largest then known, including the philosopher's original manuscripts and unpublished writings. As head of the Peripatetic school he displayed an all-round versatility not unworthy of Aristotle himself, and was the reputed author of 227 works. His authority remained for many years paramount in logic, psychology, ethics, politics, rhetoric, physics, and metaphysics, in all of which subjects he preserved the lines of his predecessor, while supplementing most of them wherever they seemed defective. His writings are in great part lost, particularly the valuable zoological series in which he dealt with the instincts and habits of animals; but we still possess his History of Plants, his Causes of Plants, his treatises on Stones and on Fire. In his hands ancient botany attained its highest development, and after him it seems to have been cultivated only in its relation to medicine. His XXX. Characters is another of his extant works—a masterly delineation of moral types, which, however, some scholars assume to be a later compilation from a more discursive original of his. His death is fixed at 286 B.C., after directing for a whole generation the Peripatetic school, which attracted many disciples from all parts of the Hellenic world. As its permanent seat of instruction he bequeathed to it his house, garden, and colonnades.
For a full and accurate review of his writings as a naturalist, see Die Pharmacie bei den alten Culturvölkern, by Dr J. Berendes (vol. i. 1891), and for his position in Ethics the masterly edition of the Characters, with introduction and trans. by Professor Jebb (1878). The best editions are those of Schneider and Vimmer. See also Usener's Collectanea Theophrastea.