Spinoza's "magnum opus", the "Ethics", was published posthumously in the year of his death. The work opposed Descartes' philosophy of mind–body dualism and earned Spinoza recognition as one of Western philosophy's most important thinkers. In it, "Spinoza wrote the last indisputable Latin masterpiece, and one in which the refined conceptions of medieval philosophy are finally turned against themselves and destroyed entirely". Hegel said, "The fact is that Spinoza is made a testing-point in modern philosophy, so that it may really be said: You are either a Spinozist or not a philosopher at all." His philosophical accomplishments and moral character prompted Gilles Deleuze to name him "the 'prince' of philosophers".