The Swiss mathematician Leonhard Euler (1707–1783) was probably the most prolific mathematician in recorded history. He helped unify the systems of calculus first created independently by Leibniz and Newton. He made key contributions to geometry, number theory, real and complex analysis, and many other areas of mathematics. In 1736, Euler published a major work in mechanics, appropriately called *Mechanica*, which introduced methods of mathematical analysis to solve complex problems. Later, he published another work on hydrostatics and rigid bodies, and he did tremendous work on celestial mechanics and the mechanics of fluids. He even published a 775-page work just on the motion of the Moon.