Pauli makes a critical comment on Fierz's paper on Jordan's theory.

Pauli talks more about the indefinite metric which Pauli rejects.

Addendum to appendix of last letter, giving Pauli' conclusion. The discussion with Heisenberg has not brought him nearer to a possibility of interpreting physically the formulae derived from the indefinite metric.

Pauli comments on a paper by Salam and his B-field. He writes about the open question whether the rest mass of the B-particles is zero. He writes about the conservation of lepton charge, two-component theory and CP or T symmetry. He writes about Lüders' and Pauli's theorem, and Schwinger's previous theorem. He makes remarks on his calculations last autumn, connected with the "Pruett-factor".

Pauli suggests suspending the discussion until new points of view emerge.

Pauli is pleased whith Heisenberg's letter of 24 February and continues the discussion.

Pauli writes about Gorter's preprint on 58 co-experiments and about a note by Salam.

Pauli talks about his plans for a journey to England and Copenhagen. He writes more about parity violation.

Pauli asks which of Touschek's papers he could read. He writes about Leiden's paper on Gorter's experiments with orientated 58 co-nuclear spins which are in good agreement with the two-component theory.

Pauli makes a comment on Fierz's letter. He writes that equations which cannot be derived from a variation principle must fail in the end, both in the mechanics of points and in classical field theory. He speaks about a book by Jordan and he speculates on the origin of life. Pauli suspects that its first beginnings are non-reproductive phenomena like Jung's "synchronic" phenomena.