There's a story about a carpenter who walked into a library, picked up a copy of Serge Lang's book "Algebra", skimmed through the first page where he proves uni

There's a story about a carpenter who walked into a library, picked up a copy of Serge Lang's book "Algebra", skimmed through the first page where he proves uniqueness of the identity in a monoid, was surprised at how ironclad the argument was, and became a mathematician to study it more. I forget his name, or where I heard it.