Euler and the Bridges of Königsberg

The great Swiss mathematician Leonard Euler was born in 1707 in Basel and published his first paper at the age of 19. From then until his death in St Petersburg in 1783, he wrote a stream of papers on subjects from algebra and calculus to geometry and number theory, to acoustics and music, the theory of lenses, the motion of ships, the atmospheres of the moon and Venus, and many other topics, making him by far the most productive mathematician of all time.

His wonderful memory helped him. He knew Virgil's Aeniad by heart and could start ‘reading’ it from memory, given any page number. He could also do complex calculations in his head: when two pupils summed the first 17 terms of a series but couldn't agree on the fiftieth decimal place, Euler corrected them by doing the calculation mentally. Nothing distracted him, not even his 13 children or his blindness in 1771 after a cataract operation failed: he simply dictated his results to an assistant and wrote his papers faster than ever, nearly 900 in all. Thirty years after his death, the Academy in St Petersburg was still publishing his original works.