 Crusius’ major philosophical works followed in quick succession. He published his textbook on ethics, the Anweisung vernünftig zu Leben (Guide to Rational Living) in 1744; this was followed by the elaboration of his metaphysics, Entwurf der nothwendigen Vernunft-Wahrheiten (Sketch of the Necessary Truths of Reason) in 1745; and a text in logic, the Weg zur Gewißheit und Zuverläßigkeit der menschlichen Erkenntiß (Path to the Certainty and Reliability of Human Cognition) was published in 1747 (a final philosophical treatise on physics followed in 1749). As an ordinary professorship in philosophy was not available, Crusius joined the theology faculty at Leipzig in 1750. While he remained a member of the philosophy faculty and continued his lectures (and revised his previous publications for later editions), from this point on his original publications are devoted to theological topics. He died in Leipzig on 18 October 1775.