Berlin, 5 June 1925

Further work on the quantum problem, and on the great potential of Jewish unification.

'I am firmly convinced that all the Weyl-Eddington-Schouten chain of reasoning leads to nothing physically useful and have now found another track, which is more physically founded. The quantum problem seems to me to require something like a special scalar, for whose introduction I have found a plausible path. Otherwise I have worked out and further established a quantum theory of ideal gases, which now seems confirmed in the results'.

Einstein returned on 1 June from a journey to South America, which was fun ('eine grosse Hetz') but without much interest, although it at least offered a few weeks of peace and quiet during the sea crossings. He may come to Switzerland for a League of Nations meeting, although he expresses renewed scepticism about the efficacy of the organisation. His visit to the Americas has at least convinced him of the qualities of Europeans: his trip has exposed him to people 'free of prejudices, but for the most part hollow and uninteresting ... Wherever I go I am received with enthusiasm by the Jews, as I am for them a sort of symbol of collaboration between Jews. I take great pleasure in this, as I expect great things from the united efforts of the Jews'.