Translation by Pedro H. G. MunizIn this paper, I am interested in the Medicina mentis, a book published in 1689 (2nd ed. 1695) by the former disciple of Spinoza, Ehrenfried Walther von Tschirnhaus. I show how, without ever mentioning Spinoza by name, Tschirnhaus borrows greatly from Spinoza’s theory of common notions when elaborating what he calls his ars inveniendi. Based on Tschirnhaus’ correspondence with Spinoza, and with Leibniz about Spinoza, I also show how Tschirnhaus very likely profited from personal conversations he had with Spinoza about a treatise planned but never completed by the latter—“another treatise” which was dedicated, exactly, to the theory of common notions, in both a methodological and an epistemological context.Tra...