Euler stayed at St. Petersburg from 1727 to 1741, however the political political situation in Russia at this time was very unstable, government spies were everywhere, purges where the rule. When later asked about his retisence to speak by the Queen of Prussia, Euler is reported to have replied `Madam, I come from a country where if you speak, you are hanged'.

In 1741 Euler accepted a new post at the Berlin academy, court mathematician to Fredrick the Great of Prussia, Euler stayed in this position for 25 years. By 1766 the political situation in Russia had settled down and Catherine the Great of Russia was in power. At this time Euler accepted an new appointment in St. Petersburgh where he was hailed as a returning hero. Now 59 Euler started to lose his sight, but amazingly he managed to keep up his mathematical work by dictating to his sons. He was apparently able to do extensive and complex calculations in his head, remembering every step so that he could recite them for his sons to record. Euler died in 1783 at the age of 76, active to the last.

Euler's work was prodigous, he published more than 500 books and papers during his lifetime, with another 400 appearing posthumously, his collected works span 74 volumes. Euler worked in nearly every feild of mathematics, and theoretical physics enhancing and unifying what he found.

Euler was also active in the popularisation of mathematics and science, he designed textbooks for Russian elementary schools, his lessons to Frederick the Great's neice Princess Anhalt-Dessau where written up in Letters to a German Princess, which was translated into seven languages and became a best seller. In addition Euler represents the last step in the development of totally modern notations. He is acredited with the first use of the Greek letter Pi to represent the ratio of the circumference of a cicle to its diameter, e to represent the base of the natural logarithm and i for sqrt(-1).