Pauli writes on the "universal length" and about his discussions with Stern concerning the connection of entropy and observation.

Pauli announces that he is going to send Bohr a copy of his article for the Einstein volume containing a survey of the epistemological situation in quantum mechanics and is eager to hear Bohr's opinion on it. He also asks Bohr to paper for the issue of "Dialectica" on complementarity and talks about a group of experimental physicists in Rome.

Pauli congratulates Bohr on his article for the Einstein volume and makes some little corrections. He announces an international physics conference in Zürich and hopes that Bohr will accept an invitation.

Pauli is glad to have Bohr's letter of May 11th and he hopes that Bohr will soon be back in Copenhagen. Einstein has sent Pauli an article for "Dialectica", which essentially repeats his old arguments. Pauli encloses copies of his letter to Einstein and also his reply. Pauli did not agree with Einstein's point of view expressed in his letter and he did not continue this correspondence. Pauli urgently needs Bohr's promised article for "Dialectica". A short address clarifying some concepts used by Bohr would be sufficient without any discussions of historical questions. They all hope that Bohr will be able to come to the conference in Zürich.

Pauli thanks Bohr for his letter of the 16th October 1948, containing the revised version of the Einstein article and the "Dialectica" article. He makes some comments on his editorial survey. He asks Bohr about a contribution to a physics meeting in July 1949. He also reminds him of Sommerfeld's 80th birthday.

Pauli was glad to have Bohr's recent letter and was particularly glad to hear that part II of the joint paper by Bohr and Rosenfeld made such good progress. However, he goes on to say that "there is one important point regarding the consequences of the quantum-electrodynamical formalism for charge- (and current-) fluctuations (positron-theory) on which he cannot agree with you: according to my opinion Heisenberg was entirely right in his claim of unsharp limitations of either the space or the time domain in which the charge (or current) fluctuation is considered in contrast to the case of energy (and momentum) fluctuation of the radiation (where a sharp limitation of the space-time region is sufficient to guarantee a finite value of the square of the mean value of the field strenght over this domain)". The letter also contains other scientific problems.

This letter is mostly about Oppenheimer, his present situation and his future.

Pauli talks to Bohr about his opinion concerning the Bertrand Russell document on peace. He also writes about their relativity meeting in Bern. Max Born will try to be there.

Pauli says that he has not recently produced anything new in physics, partly because of many deaths in his environment in Zurich, including Placzek, Pauli's father, the wife of Carl G Jung and Hermann Weyl victim of a heart attack. He also speaks about his latest trip to Hamburg, where he saw Jordan, the astronomer Heckman and his former "chief" Lenz. Lenz will retire next spring, and there were some discussions about his succession. He talks to Bohr about the project of a Scandinavian Institute of Physics in Copenhagen. Pauli has also received another political letter from Bernadotte regarding the "Mainau statement" and asks Bohr for his opinion.

Pauli replies to a question from Bohr, whether an H-theorem can be derived from the point of view of quantum mechanics. He has made no progress in quantum electrodynamics and thinks that a completely new idea is still missing. He writes about Kronig's works and about Nature's introductory remark to Bohr's article.