Spinoza shared ethical beliefs with ancient Epicureans, in renouncing ethics beyond the material world, although Epicureans focused more on physical pleasure and Spinoza more on emotional wellbeing. Encapsulated at the start in his "Treatise on the Improvement of the Understanding" ("Tractatus de intellectus emendatione") is the core of Spinoza's ethical philosophy, what he held to be the true and final good. Spinoza held good and evil to be relative concepts, claiming that nothing is intrinsically good or bad except relative to a particularity. Things that had classically been seen as good or evil, Spinoza argued, were simply good or bad for humans. Spinoza believes in a deterministic universe in which "All things in nature proceed from certain necessity and with the utmost perfection." Nothing happens by chance in Spinoza's world, and nothing is contingent.