Before a suspension bridge can hold morning traffic, before fluid dynamics can lift a plane, before encryption can secure your wallet, someone had to write the syntax that makes those calculations possible. Most of that syntax was standardized by one 18th-century Swiss polymath. This episode is a deep dive into Leonhard Euler, the man who built the mathematical alphabet of the modern world.

We trace his ascent from the University of Basel under Johann Bernoulli to the Imperial Russian Academy in St. Petersburg, his dozen turbulent years at Frederick the Great's Berlin Academy, and his eventual return to Russia under Catherine the Great. We unpack the notation we still use without thinking (e for the natural base, i for the imaginary unit, the modern use of f(x) for functions, sigma for sums) and the landmark results that anchored entire fields, including Euler's identity (e to the i pi plus one equals zero), the foundations of graph theory in the Seven Bridges of Königsberg, and the mechanics of fluid flow.

Then we turn to the human story: the Sanssouci fountains fiasco that Frederick mocked him for, his progressive blindness, and the second act of his career, in which he produced about half of his collected work after losing his sight by relying on memory and dictation. The episode closes with a sharp reframing: Euler did not just overcome his blindness, he used it as a focus instrument.

Subscribe to pplpod for more deep dives into the people who built the modern mind. Topics: Leonhard Euler, mathematical notation, Euler's identity, graph theory, Seven Bridges of Königsberg, fluid dynamics, Sanssouci, Catherine the Great, Frederick the Great, history of mathematics.

Source credit: Research for this episode included Wikipedia articles accessed 5/3/2026. Wikipedia text is licensed under CC BY-SA 4.0; content here is summarized/adapted in original wording for commentary and educational use.