On April 15, 1707, Leonhard Euler was born in Switzerland. If you are not a mathematician, the name may mean little to you, but he is important enough to us math folk that mathematical societies around the world have proclaimed this Euler Year to commemorate the occasion.
Leonhard Euler (pronounced Leonard Oyler) is widely considered one the four great mathematicans prior to 1850, though he was not on that same list 100 years ago. For more on his improving status among mathematicians, you can go to http://binomial.csueastbay.edu/EulerNote1.html
As you can see, he is honored in the country of his birth on the 10 franc note, making him kind of like the Swiss Alexander Hamilton, except nobody ever shot Euler in a duel; he is almost an exact contemporary of Ben Franklin, both their birth dates and death dates being just a few years apart. He was also honored by the Soviet Union and East Germany, not because he was some kind of proto-commie, but instead because he was important both to Russian and Prussian science, as he worked in the St. Petersburg Academy for Catherine the Great and the Prussian Academy for Frederick the Great. Pretty much, if you wanted to be a "The Great" that century, getting Euler to work for you was a must.
There will be more Euler-centric posts this week to honor him in his tricentennial year, with more reasons why he is My Favorite Lenny.