Heisenberg asks questions about the theory of holes.

Pauli emphasizes that in spite of the difficulties his attitude to the theory of holes is not negative. He gives some comments on the magnetic moment of nuclei and of the neutron. If the laws of nature are completely symmetrical with regard to positive and negative electricity, a negative proton should also exist and the free neutron should exist in two states, if its magnetic moment is different from zero.

Pauli reacts in a very positive way on Heisenberg's letter of the 6 November 1933 and hopes he will continue his calculations.

Pauli proves that Heisenberg's theory given in his letter of the 6 November 1933 is identical with a former theory developed by Pauli and Heisenberg.

Heisenberg writes about Pauli's objections to his exchange-relations.

Heisenberg revokes his remarks made in the last letter.

Pauli agrees with Heisenberg's pessimism regarding infinite energies, but he thinks one should try to separate the problem of self-energy from that of the hole theory.

Heisenberg gives new calculations about the theory of holes. He writes about the gauge-invariance of certain expressions, about the problem of self-energy. he talks on the necessity for theories with infinite degrees of freedom and a quadratic wave equation should be possible in the case of absence of external fields.

Pauli does not believe that the theory of holes can be improved without essentially new ideas.

Heisenberg gives a few corrections to the last letter.