Not the doctor — the geometer. Hippocrates of Chios (fl. 5th century BCE) was the first to systematically square curvilinear figures and came tantalizingly close to solving the infamous problem of squaring the circle. He introduced the idea of geometric “reduction,” where complex problems bow to simpler ones. Once a merchant (until pirates ruined that), he turned to mathematics and never looked back. His “lunes” still shine in geometry textbooks — and not just because they’re shaped like moons.