All right, it’s April 13th, and you are all cowering under your desks in fear of something bad-lucky happening. Cheer up, though: Sunday is April 15th, the tercentenary of Leonhard Euler, one of–by everyone’s reckoning–the top five mathematicians that ever lived. Arts & Letters has a piece about him here, though not half as good (nor as long) as my piece in the forthcoming Wilson Quarterly. The correct pronunciation of Euler’s name can be deduced from the following tribute:Leonhard EulerWas math’s most prolific toiler.Only a lifetime of insomniaCould have produced his Opera Omnia.