Eudoxus of Cnidus

Eudoxus of Cnidus was an ancient Greek astronomer, mathematician, physician and lawmaker who lived roughly from 390 to 340 BC and studied under Archytas and Plato. In mathematics he developed the method of exhaustion, a precursor to integral calculus, and established a rigorous theory of proportion able to handle irrational and continuous quantities, work that became foundational to later geometry and directly influenced Euclid Elements. In astronomy he proposed a model of concentric spheres to explain the observed motions of the planets using combinations of uniform circular motion.