Fierz withdraws an incorrect remark from his letter of the 17 October 1952.

Fierz replies to Pauli's letter and manuscript of his paper "On the Hamiltonian structure of non-local field theories."

Fierz summarizes tasks and problems of joining atomistic mechanics and thermodynamics. He discusses proof of ergodic hypothesis and statistical behaviour of quantum probability for a macroscopic system.

Pauli writes about his intention to write an essay on space, time and God in Newton's writings.

Fierz writes on Newton's philosophical background, between Descartes' rationalism and Hume's scepticism.

Fierz thanks Pauli for the offprint of a paper on gravitational waves. It seems to follow from it that the statement about non-existence of gravitational radiation is unjustified.

Fierz writes on gravitational waves, on the symbolic significance of the blue colour and on Henry More's third "Divine Dialogue".

Fierz writes on the ethical value of music and he sends some quotations from Pauli-Wissowa on the Greek attitude to this problem.

Fierz writes on the concept of space in Plato and in the 17th century, and its connection with the philosophy of complementarity.

Fierz replies to Pauli's question about the representation of the inhomogeneous groups: the orthogonal group and the Lorentz group.