Considered one of the great rationalists of 17th-century philosophy, Spinoza's posthumous masterpiece Ethics, in which he opposed Descartes's mind–body dualism, has earned him recognition as one of Western philosophy's most important thinkers. The first part of the book addresses the relationship between God and the universe. The second part focuses on the human mind and body. In the third part, Spinoza argues that all things, including human beings, strive to persevere in their being. The fourth part analyzes human passions.The fifth part argues that reason can govern the affects in the pursuit of virtue.