Death of Spinoza (1677) — Proving Philosophy Like Geometry

Baruch Spinoza died in The Hague on February 21, 1677. His masterwork Ethics was written in the style of Euclid's Elements — opening with definitions and axioms, then deriving all propositions about God, human nature, and the good life by strict logical proof. Each proposition is labelled Q.E.D. The ambition was breathtaking: if ethics could be proved rather than felt, disagreement would be as absurd as disagreeing with Pythagoras. Whether Spinoza succeeded is fiercely debated. But the method itself was revolutionary: the idea that deductive mathematics is a model for all rigorous thought was spreading from geometry into philosophy, physics, and eventually into the foundations of logic.