Sommerfeld expresses his admiration over Pauli's "Handbuch-article on Quanta". He says that Schrödinger's wave mechanics does not yet solve the riddle of quanta.

Sommerfeld talks about his article in the Planck issue of Annalen Phys. and about his interest in non-integer quantum numbers. He is optimistic about the future of physics and thinks that someone will soon understand the elementary particles, the Pauli-principle and the divergencies. He is less optimistic about the future of civilization.

Sommerfeld thanks Pauli for his article in Naturwissenschaften in honour of Sommerfeld's 80th birthday.

Sommerfeld suggests that Pauli writes a review on his "optics".

Symanzik makes some addition to the last letter.