A great physical theory like Schrodinger's wave mechanics, when it is confirmed, takes on its own impersonal existence in the course of time, becomes completely detached from its originator, and is finally received as self-evident. In this way one forgets how many inner straggles, hopes, and disappointments were bound up with its beginnings and one forgets too all the pros and cons of contemporary reactions to it. This more personal side can be reawakened into life if there are contemporary letters like the ones reproduced here.