Lambert’s exceptional range of work is still under-appreciated. Among much else, he developed a pioneering form of non-Euclidean geometry, proved π to be irrational, and was among the first to understand that the Milky Way is a spiral nebula. He met d’Alembert in Paris during a 2-year trip through Europe. Euler invited him to take up a position in Berlin, where Lagrange was also based; as colleagues they extended his work, but Euler and he quarreled, Euler moving on. Bode (with whom he founded an influential astronomical yearbook) and Sulzer were other Berlin colleagues. Kant, a correspondent, greatly admired him.