Work on quantum theory whilst recovering from an attack of illness – and scepticism about new medical practices.

Einstein reports an improvement in his health (after his abdominal disorder had flared up during his summer visit to Switzerland): 'I am still very well. I had a single small attack, but it's now passed. It is touching how you both worry about me. The provender is good, and I rest a lot. Today I applied quantum theory to rigid bodies (freely moving)'. He is also touched that Anna Besso is offering to look after Mileva Einstein (who had spent August and September in hospital). His younger son Eduard ('Tete') must return to Zurich from Arosa, where he has been receiving medical treatment, as Einstein no longer has enough money to pay for his stay (his finances a victim of wartime exchange rates): 'I do not believe in the new medical magic with X-rays. I am at the point that only post mortem diagnoses inspire confidence, nothing else'. He urges Besso to come and visit him in his new apartment in Berlin: 'Please accustom yourself slowly to the idea!'.