Pauli received an elaboration of Jauch's lecture.

Pauli discusses on his work on unipolar induction and on his reactions to Dirac's theory of the single magnetic pole.

Pauli writes on the problem of relativistic invariant regularization and Stückelberg's view on it.

Pauli has waited quite a while since receiving Bohr's letter of February 8, because he hoped to be able to say something on Schwinger's answer to his long letter. Pauli did not receive any answer. One of Schwinger's pupils contacted Pauli, from which he has the impression that Schwinger takes the matter seriously. Meanwhile Pauli and Villars have completed the calculations mentioned at the end of of Pauli's letter to Schwinger. He has almost no doubts on the correctness of his results for the electron magnetic moment, although the argument is somewhat different from his own. Villars and Pauli will send a joint paper with all their calculations to the Einstein issue of the Rev. of Mod. Physics which is edited by Pais. He also says that the work on quantum electrodynamics in their institute is proceeding well.

Pauli writes about a paper by Villars and himself for the Einstein issue of the Rev. Mod. Phys. which will be sent off in a week. He asks if a certain result is already known. He writes about self-energy and "self-stress" of the electron. He also mentions Kramer's state of health.

Pauli writes about Feynman's paper on the positron. He adds a suggestion of a procedure which disregards the particle and follows up the changes of charge in space and time.

Pauli thanks Bohr for his last letter and for the enclosed page by Rosenfeld, which he is now returning. He agrees that there is an elementary error on this page, which he explains further.

In this letter, Pauli speculates about the connection between synchronicity and Leibniz's synchronized monads. He writes on the necessity for introducing into science a principle more general than causality and similar to that of the "correspondentia" of the Middle Ages which would give significance both to causality and synchronicity in a wider frame.

Pauli writes on the symbol of trinity.

Pauli will attend the inauguration of new institute in Lund.