"Ethics" by Benedictus de Spinoza is a philosophical treatise written between 1661 and 1675. Using Euclid's geometric method, Spinoza constructs a radical philosophical system from definitions and axioms, deriving propositions about God, nature, mind, and human emotion. He argues that God and the universe are one, that mind and body are unified, and that human beings lack free will. Through logical demonstration, Spinoza presents a deterministic vision where everything follows necessarily from the nature of existence itself.