Pauli asks for a reprint of Casimir's paper on microcospic reversibility in connection with a lecture on problems of the statistical theory of heat.

Pauli agrees with Casimir that quantum electrodynamics have entered a new phase and refers to the recently discovered fact that the magnetic moment of an electron at rest is somewhat larger than Bohr's magneton.

Pauli is sending a selection of journals, but he thinks that Dutch physicist's expectations concerning the content of American and English periodicals for the years 1940 - 1945 are too high. However, some interesting work has been done in the neutral countries and Russia. In the USA some progress has been made in more technical fields, like microwave, radar and heavy cores. Pauli did not contribute to the secret work, but he worked alone on meson theory and quantum electrodynamics. He was not able to solve any real problem in this domain. The most interesting subjects are now Amaldi's experiments on neutron-proton-scattering and its discussion by Hulthèn and Wentel. Pauli will send Casimir and Rosenfeld a copy of his M.I.T. lectures on meson theory, which will soon be available. He says that the problem of the nature of nuclear forces is no more solved than it was in 1940, and he does not expect the secret material to help when it is published. Pauli encloses Onsäger's solution of a two-dimensional Ising model which he considers a masterpiece. Pauli says that he has been offered a professorship at Princeton, but since he is still a professor at Zurich he feels some obligation towards them and plans to postpone his decision until he has visited Zurich. He discusses the post-war situation in Europe and the U.S.A. and says that he feels himself to be a European.

Tells about a report by Schein at a meeting in New York on artificial meson production.

Pauli gives an impression of his visit to Stockholm and Copenhagen on the occasion of his Nobel-lecture. He regrets that an exhibition of Kelder's sculptures cannot be arranged in Zürich.