Pauli offers more criticsms of Klein's Bohr-Festschrift article.

Pauli says that he has written a first version of his Mainz lecture about 'relation metaphysics' (Heilserkenntnis). He discusses some ideas on the subject, citing among others E. A. Burtt's "The Metaphysical Foundations on Modern Science" and B. Russell's "History of Western Philosophy".

Pauli explains his use of the adjectives "positivistic", "realistic", "idealistic" and "phenomenalistic" as logically linked aspects of the world and as corresponding features of a theory.

Referring to Bohr's lecture "On the unity of knowledge", Pauli mentions his misunderstandings with Bohr concerning the concept of the "detached observer", the concept of reality in atomic physics, Bohr's conception of "complementarity" as foundation of a world religion, and the use of the concept "antinomic" (antinomisch).