Pauli gives a more precise formulation to the problem of dipole ghosts and an another solution. He also discusses approximation through complex roots.

Pauli replies to Källén's letter of the 10 and the 12 January 1957. He talks about of his discussion with Fierz of the time-dependent solutions for dipole ghosts. Fierz criticizes Pauli's continuity argument for the S-matrix.

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

Pauli refers to a paper by Heisenberg and explains a passage which was misinterpreted by Källén.

Pauli writes about another mathematical comment on Heisenberg's paper.

Pauli encloses a letter to Springer. He talks about a new paper by Schwinger on elementary particles. He writes on the logical connection of Källén's recent results to an example given by Jost last spring. He also talks about Thirring's model.

Pauli replies to Källén's letter of the 13 December 1957. Pauli agrees with him that the indefinite metric is the correct way. He talks about the macroscopic space-time description with complex roots and the Bisection of zero-states in parts corresponding to the upper and lower half-plane which must be connected with the difference between observed object and observing subject. By this bisection symmetric violations are introduced in a most natural way. He writes on his discussion with Heisenberg and on complex ghosts in weak interactions.

Pauli talks about the logical possibility of getting particles with mass different of zero in a world with $\gamma_{s}$-invariance and hints at another "unconventional" solution of the problem.

Pauli writes about some free time he spent with A. Thellung, and about his (Pauli's) relationship with the Kramers.

Pauli replies to Kemmer's letter (14 February) to Fierz. He talks about his forthcoming lectures on field quantization and gives some remarks on Dirac's equations for particles with higher spin.