Pauli comments on Fierz's difficulties in treating the problem of the spin-electron in a magnetic field. He makes some remarks concerning Kepler's astrological ideas.

Pauli attached to this letter a copy of a letter he wrote to Einstein, in which Pauli formulates his view on the physical reality and its description by quantum mechanics. Also attached is Einstein's answer to Pauli's letter (copy of the letter Einstein_0010r).

Pauli writes on the concept of individuality in quantum physics and in psychology, on the identity of perception and intuition in the unconscious, and its connection with the concept of time.

In this letter Pauli raises the question whether Gibb's variation of thermodynamical functions preceeded Planck's work or not.

Pauli asks Fierz about Leibniz's principle of the identity of indiscernibles, which is mentioned by Weyl in connection with the exclusion principle.

Pauli makes some remarks on a paper written by Heisenberg.

Pauli comments on two treatises by Huygens, the "Traité de la lumière" and the "Discours de la cause de la pesanteur". He also writes on Descartes' theory of vortices.

Pauli gives further comments on Bohm's ideas, in particular on the hidden parameters.

Pauli gives a critical comment on a letter by de Broglie and his attempt to combine a deterministic picture with the wave-mechanical probability,

Pauli replies to Fierz's letters on thermodynamics. He refers to papers by V Neumann, Szillard and Einstein. He also writes on different formulations of entropy which have the same meaning.