on many subjects, who in 1761 proved that π is an irrational number. He introduced the standard notation for hyperbolic functions, investigated hyperbolic triangles, and came close to discovering non-Euclidean geometry.
Philosophy
Largely self-taught, Lambert became one of the most distinguished German scientists and mathematicians of the eighteenth century. Philosophically he attempted to ally rationalism in metaphysics with the mathematical treatment of reasoning and logic, continuing the tradition of Leibniz. He was much admired by Kant.