3 8 2 D O C U M E N T S 3 9 7 , 3 9 8 O C T O B E R 1 9 2 6 397. To Heinrich Zangger [Berlin,] 29 October 1926 Dear Zangger, Of course it means absolutely nothing that I have not written you sooner.[1] The only reason is that so much keeps assailing me that I rarely have time for myself. I am very pleased that people here have so much confidence in you and that the es- tablishment of the Institute for Forensic Medicine is being turned over to you.[2] That is actually quite magnanimous and has no taint of prestige politics at all. It is a good sign for the faculty I am very pleased that you are coming here and that, in this way, I can be with you again as in the old days. Let me know soon when you’re coming. I am very curious how everything here looks through your eyes. The drag- on teeth of my youth[3] (quanta) have sprouted so gloriously that I am scared and frightened. The theories chase each other, and, still, so little is understood. Albert concerns me due to his planned production line of children with double genetic pre- dispositions. I thank you again for the effort that you exerted with him.[4] Nothing more can be done. Warm regards, your A. Einstein 398. From Arnold Sommerfeld Munich, 31 October 1926 Dear Einstein, Anschütz tells me that your refusal regarding our guest lectures is perhaps not definite.[1] Please write me if you feel the slightest inclination to come. I just did not want to bother you with any counterproposals. Nevertheless, the chair of the committee on guest lectures must still have a say about the time of your coming. But above all, the following: For the general lectures (attendees from all depart- ments!), exclusively general themes should be considered, hence more philosoph- ical ones, e.g., “on the origin of our conception of space and time” or “epistemology in physics,” or even: “on the finiteness of the world.” The most re- cent problems, which, as I hear, you are brooding over with success (good luck on that!), can only be addressed by you in our physics colloquium, where such things will be very welcome. Our guest lectures do primarily involve a general audience. During the summer vacation I read the popular book by Eddington, Space Time Gravitation,[2] and was enchanted by it. I know of no other book written as well as that. Best wishes from your A. Sommerfeld