Crusius was born in
Leuna in the
Electorate of Saxony. He was educated at the
University of Leipzig, and became
extraordinary professor of theology there in 1744,
ordinary professor in 1750, and senior (university officer) in 1773. and also explicitly refuted Crusius' characterization of Spirit in a footnote of his
Prolegomena to Any Future Metaphysics: "Crusius alone thought of a compromise: that a Spirit, who can neither err nor deceive, implanted these laws in us originally. But since false principles often intrude themselves, as indeed the very system of this man shows in not a few examples, we are involved in difficulties as to the use of such a principle in the absence of sure criteria to distinguish the genuine origin from the spurious, as we never can know certainly what the Spirit of truth or the father of lies may have instilled into us." Kant also owned
Anweisung,
Entwurf, and
Anleitung. Crusius's later life was devoted to theology. He led the party in the university which became known as the "Crusianer" as opposed to the "Ernestianer," the followers of
Johann August Ernesti. The two professors adopted opposite methods of exegesis. Ernesti wished to subject the Scripture in the same way as other ancient books; Crusius held firmly to orthodox ecclesiastical tradition. He died in
Leipzig. ==Philosophical work==