Heisenberg writes of the distribution of their common pre print. He suggests the next steps as regards the paper and its disposition.

Heisenberg sends Pauli his Geneva lecture and notes of the discussion, prepared by Ferretti. He adds a correction of the results for the Pi-eigenvalues, after Schlieder's discovery of a mistake in the calculations.

Heisenberg writes about the enumeration of quantum numbers and in particular the value for k.

Heisenberg writes more about the polarization of Stark effect components, about Heisenberg's new quantum mechanics, about the principle of the use of "observables"and about the equations for the harmonic and anharmonic oscillators.

Heisenberg replies to Pauli's calculations on hydrogen according to quantum mechanics and makes some remarks on his results.

The letter includes remarks on a paper by Pauli, on a second paper by himself on ferromagnetism for the Sommerfeld-Festschrift and on Dirac's theory.

Heisenberg sends Pauli the manuscript of a paper on elementary particles for criticism. The starting point is not quantum electrodynamics but a kind of general philosophy of elementary particles. He gives some comments on his manuscript. The fact that protons do not decay into positrons and photons must be based on a conservation law for nucleons.

Heisenberg states his view on the question of the field theory and emphasizes the significance of the Möller-Kristensen theory as a well analyzed example for further theories of this type.

Heisenberg replies to Pauli's letter. He agrees with him as to the insufficiency of the concept of causality for the explanation of evolution. He also expresses doubts as to whether Pauli's concept of "sinnoller Zufall" can lead to a better biological evolution. The second part of the letter deals with Heisenberg's ideas about a quantized field theory.