Swiss mathematician Leonhard Euler (1707–1783) is considered to be one of the most prolific mathematicians who ever lived. In fact, his accomplishments are beyond the scope of this text. Suffice it to say that his collected works number more than seventy volumes, with contributions in pure and applied mathematics, including the calculus of variations, analysis, number theory, algebra, geometry, trigonometry, analytical mechanics, hydrodynamics, and the lunar theory (calculation of the motion of the moon). Euler was one of the first to develop the methods of the calculus on a wide scale. His most famous book, Elements, rapidly became a classic; and he wrote a geometry textbook (Yale University was the first American college to use the text).

Although half-blind for much of his life—and totally blind for his last seventeen years—he still had a near-legendary skill at calculation. Among his discoveries are the differential equation named for him (a formula relating the number of faces, edges, and vertices of a polyhedron, although Euler’s formula was discovered earlier by René Descartes); and a famous equation connecting five fundamental numbers in mathematics. Like many in the Bernoulli family, Euler eventually worked at the Academy of Sciences in St. Petersburg, Russia, a center of learning founded by Peter the Great.