Leonhard Euler (1707–1783) had such a crazy, insane, accomplished life, it’s unbelievable. When you describe Euler, your first sentence is just a mash-up of insane accomplishments. He was a brilliant mathematician, physicist, astronomer, logician, engineer, and music theorist. No exaggeration: He was world-class in all of these fields. He was perhaps the greatest mathematician who ever lived, and the most prolific. Euler published over 800 extraordinary papers in mathematics alone. He grew up in Basel, Switzerland. His dad was a pastor and he lived a regular life. He was a kind-hearted person from a family of regular folks. His genius expressed itself early, and he entered the University of Basel at age 13. At 19, he’d already finished his Ph.D. on the propagation of sound. He started his career in an era of political turmoil and erratic funding. He considered himself lucky to get a university job in St. Petersburg, Russia. Despite his massive output, he didn’t make any real money until 40 years later, when Catherine the Great came to power. He was always up against intrigue, instability, and the suspicion of foreigners. He maintained employment because of his unbelievable diligence and incredible ability to get along with folks. He and his wife, Katharina, had 13 children. I’m not sure if Euler ever had a private office. If so, he didn’t use it. When he wasn’t teaching or advising, he was home with the kiddos. He made fundamental discoveries in number theory, complex analysis, and calculus while chasing toddlers around. Because of his extraordinary patience and kindness, Euler thought math should be for everyone, and made it so. He’s still the best person to read if you want to understand math. In his spare time (ha, ha) he wrote The Elements of Algebra. This amazing book is a fundamental exposition of what math is and how it works. It explains how to add two numbers together, then takes the reader all the way through algebra. Too often, math instruction is like asking for directions and receiving a series of rights and lefts. If you miss a detail, you’re lost. The Elements shows us exactly how math works, so we know precisely where we are at any point. I’ll quote some passages, because apparently I can’t help myself. The first two paragraphs: Whatever can be increased or decreased is called magnitude, or quantity. A sum of money is a quantity, because we can increase it or decrease it. It’s the same with weight, and other things like this. From this definition, it’s clear there are so many different kinds of magnitude, it would be hard to list them all. This is the origin of the different branches of mathematics. Each of them deals with a different kind of magnitude. Mathematics is the science of quantity - it investigates how quantity is measured. When he’s done explaining what math is, he explains the operations. 8. When we have to add one number to another, this is indicted by the sign +, which is placed before the second number, and is read plus. So he proceeds, baby step by baby step, to take us from absolutely elementary mathematics all the way through algebra. Euler believed any man or woman can have perfect numeracy. We can all have a perfect understanding of how math works, and a perfect ability to work problems out mathematically. And we can all make contributions to mathematics, like we can all write poems or music, once we know the fundamentals. There’s no such thing as someone who’s bad at math. There is only flawed teaching, which skips steps, unknowingly.