McConnell makes remarks on ESP. He recommends litterature.

Pauli refers to an article by Einstein and a talk with him about the epistemological foundation of quantum mechanics. Einstein's belief that there exists an "objective" state of a system without reference to the experimental arrangement is called by Pauli "a philosophical prejudice".

Professor Bohr was very glad to have Pauli's letter of the 26th March. Since Bohr wrote last he had a visit from Delbrück, who, as Pauli knows, will stay in Göttingen this summer. This visit gave an opportunity for many instructive and interesting discussions with Danish biochemists and biologists. Bohr feels still more convinced that the general considerations about organic development, about which Bohr wrote to Pauli in January, hit a quite important point. He hopes to be able to give a more clear account of such questions in a lecture "On the unity of knowledge" at "the bicentennial celebrations" at the Columbia University in Autumn.

Fierz writes about the results of his calculations on the unitary Lorentz-transformations.