The letter describes a problem of classical theory of harmonics. It talks about Pauli's calculations on Bohr's He-Model. He looks forward to his work in Copenhagen.

Pauli wants to see Landé's manuscript. He also talks about the displacement of terms in strong fields.

Pauli thanks Landé for sending him the proofs of his paper. He comments on several points. He talks about the binding of the electrons in the He-atom.

Heisenberg writes on technicalities about a possible meeting between him and Pauli.

Heisenberg writes about the connection of the singulet-triplet distance with Pauli's exclusion principle.

Heisenberg is preparing the manuscript on He. He writes about the problem of the molecule and makes critical remarks about the physical part of Schrödinger's theory. The connection with De Broglie is not yet discovered.

Heisenberg objects to Pauli's analogy between quantum mechanics on the one hand and quantum electrodynamics and classical Maxwell theory on the other hand. There is not only Maxwell's equations must be quantized, but also the De Broglie Waves. He explains his ideas on the intuitive meaning of quantum mechanics: 1) position of the electron 2) "orbit" of the electron. He agrees with Dirac that their experiments introduce statistics 3) on the "velocity" of the electron. 4)the transition from micro- to macro-mechanics. He writes that every new observation defines a new state. There are a few examples as illustrations.