Pauli asks for details about Gürsey's formalism with a non-degenerate vacuum. He enumerates several problems which worry him, e.g. mirror states, classification of elementary particles, etc...

Pauli writes on the treatment of the eigenvalue problem. The only existing method is the Tamm-Dancoff approximation but Pauli does not believe in it. He will possibly work on the problem with Gürsey. He speaks of a principal difficulty of model which is analogous to that in the "neutrino-theory of light". In the spinor model Pi-mesons and photons are composed of real states and only formally existing mirror states which must be forbidden. There is a discussion of the difficulties resulting from this.

Pauli returns briefly to the mirror problem.

Pauli replies to a letter of the 24 February 1958. He writes about his work with Heisenberg in general and criticizes emphatically Heisenberg's radio publicity. He makes some remarks on biology and neo-Darwinism.

Pauli comments on the publicity given to Heisenberg's work. He does not believe that any model will explain the symmetry diminution occuring at the transition from the isogroup to electromagnetic forces. preprint of his and Heisenberg's work.

Pauli writes about the publicity given to Heisenberg in radio and press. He writes about the prospects and difficulties of his joint work with Heisenberg. He writes about his participation to the solid-state seminar in Kittel.

Pauli has heard that Landau is enthusiastic about Heisenberg's and his own attempt to incorporate the isogroup into the spinor model with indefinite metric. He enumerates several difficulties of the theory which are not yet solved.

Pauli makes further remarks on Gürsey's formulation.

Pauli comments on Heisenberg's relation with the press. He writes about his work with Heisenberg.