Pauli arranges a doctor's appointment for Heisenberg.

Pauli acknowledges receipt of Heisenberg's manuscript. He discusses some mathematical difficulties in the light of a paper by Wightman (Phs. Rev. 101, 860, 1956).

Pauli makes further remarks about the formulation of certain results in Heisenberg's manuscript.

Pauli continues his comments on Heisenberg's manuscript, especially on terminology.

Pauli talks about a paper by Thirring on "a soluble relativistic field theory", dealing with Heisenberg's spinor model in one dimension.

Pauli expresses satisfaction over his last meeting with Heisenberg and his suggestions for the solution of the parity problem and two-component theory of the neutrino. In connection with this he asks several questions on the isotope spin-space, on the Lee model and on the indefinite metric.

Pauli continues his last letter and gives some suggestions on how to fullfill Heisenberg's new research program.

Pauli clarifies some points concerning the definition of the Hilbert space I and II for the case of complex roots.

Pauli replies to Heisenberg's letter of the 3 and the 4 January. He is now beginning to think about the spinor-operators. He makes a short remark about lepton charge.

Pauli writes that he will not come to Debye's conference in Leipzig. He explains the meaning of some sentences in his Handbuch-article, especially those related to discontinuity created by observation. He explains what he means by second quantization. He asks Heisenberg's view on the uncertainity relations for field strengths.