The hame Leonhard Euler has already been referred to many times in this book. Euler was born in Basel, Switzerland, in 1707, and he studied mathematics there under Johann Bernoulli. In 1727 he accepted the chair of mathematics at the new St. Petersburg Academy formed by peter the Great. Fourteen years later he accepted the invitation of Frederick the Great to go to Berlin to head the Prussian Academy. After 25 years in this post Euler returned to St. Petersburg, remaining there until his death in 1783 when he was 76 years old.