Crusius, Christian August (krĭsˈtēän ouˈgŏst krōˈzēŏs) [key], 1715–75, German philosopher and theologian. He was educated at the Univ. of Leipzig, where he became professor of philosophy (1744) and theology (1750). He opposed the philosophies of G. W. Leibniz and Christian Wolff and strongly influenced the early writings of Immanuel Kant. None of his many works has been translated into English.