He moved forward, and behind him two more.- During his Berlin years (1741–1766), Euler was at the peak of his productivity. He wrote 380 works, 275 of which were published.
- Euler is credited for popularizing the Greek letter π (lowercase pi) to denote the ratio of a circle’s circumference to its diameter, as well as first using the notation f(x) for the value of a function, the letter i to express the imaginary unit √-1, the Greek letter Σ (capital sigma) to express summations, the Greek letter Δ (capital delta) for finite differences, and lowercase letters to represent the sides of a triangle while representing the angles as capital letters.
- Concerned about the continuing turmoil in Russia, Euler left St. Petersburg in June 1741 to take up a post at the Berlin Academy, which he had been offered by Frederick the Great of Prussia.
- Euler was a simple, devoutly religious man who never questioned the existing social order or conventional beliefs. He was, in many ways, the polar opposite of Voltaire, who enjoyed a high place of prestige at Frederick’s court.
- In St. Petersburg on 18 September 1783, after a lunch with his family, Euler was discussing the newly discovered planet Uranus and its orbit with Anders Johan Lexell when he collapsed and died from a brain hemorrhage.