Pauli letter collection: letter to Oskar Klein

Pauli reports in detail on Pais' lecture in Holland on "isotopic spin and mass quantization" and on his introduction of the "W-space". Pauli writes about Jordan's cosmological equations. Pauli thinks that Einstein's model is simpler and more convincing. He does not see the advantage of the introduction of a changing gravitational constant. The appendix contains ideas about the statistical theory of heat.