He lent Enrico the book. Two months later Enrico revealed he had mastered the material, having worked through all of the theorems and solved all the problems at the back of the book. Amidei was understandably skeptical because the book had been difficult for him as a university student and, as a result, he had never completed the proofs himself. When Fermi gave Amidei the proofs for the theorems, the older man’s doubts vanished.
