This book celebrates the 300th birthday of Leonhard Euler (1707 1783), one of the brightest stars in the mathematical firmament. The book stands as a testimonial to a mathematician of unsurpassed insight, industry, and ingenuity one who has been rightly called the master of us all. The collected articles, aimed at a mathematically literate audience, address aspects of Euler s life and work, from the biographical to the historical to the mathematical. The oldest of these was written in 1872, and the most recent dates to 2006. Some of the papers focus on Euler and his world, others describe a specific Eulerian achievement, and still others survey a branch of mathematics to which Euler contributed significantly. Along the way, the reader will encounter the Königsberg bridges, the 36-officers, Euler s constant, and the zeta function. There are papers on Euler s number theory, his calculus of variations, and his polyhedral formula. Of special note are the number and quality of authors represented here. Among the 34 contributors are some of the most illustrious mathematicians and mathematics historians of the past century e.g., Florian Cajori, Carl Boyer, George Pólya, Andre Weil, and Paul Erdös. And there are a few poems and a mnemonic just for fun.