BERTRAND RUSSELL & ALFRED NORTH WHITEHEAD – Principia Mathematica 1+1=2
Some idea of the scope and comprehensiveness of the “Principia” can be gleaned from the fact that
it takes over 360 pages to prove definitively that 1 + 1 = 2.
Today, it is widely considered to be one of the most important and seminal works in logic since Aristotle’s “Organon”. It seemed remarkably successful and resilient in its ambitious aims, and soon gained world fame for Russell and Whitehead. Indeed, it was only Gödel’s 1931 incompleteness theorem that finally showed that the “Principia” could not be both consistent and complete.
https://www.storyofmathematics.com/20th_russell.html