This biography on Christiaan Huygens (1629-1695) describes in detail how he arrived at discoveries and inventions often wrongly ascribed to Newton. The great seventeenth-century Dutch mathematician and physicist played a key role in the 'scientific revolution' and the Huygens Principle on the wave theory of light helped establish his reputation. Moreover, the discovery of Saturn's rings and the invention of the pendulum clock made him so famous that he was invited to be the first director of the French Academy of Science.