D O C U M E N T S 3 4 2 , 3 4 3 A U G U S T 1 9 2 6 3 4 3 342. To Ilse Kayser-Einstein Montana, 5 August 1926 Dear Ilse with her Lord, and dear Margot,[1] Thank you for the little card from your summer escape. I’ve become sort of an alpinist. We went from Engelberg over the Joch Pass to Engstlenalp-Meiringen and Sunday from Montana over the Rawil Pass to Lenk.[2] Hopefully, the weather is good in this grim wasteland. Here, we are leading an idyllic life, my literary son and I. Poor Grandmother is lying there in terrible condition, but, thank goodness, unaware.[3] The main thing now is that Mother[4] find some distraction, because, otherwise, she can hardly endure it. Did you hear the sad story of Miss Levi? I feel partly responsible it saddens me greatly. If only I knew how I can help them! We’re living here completely alone or, more precisely, just the two of us in a small inn the idyll will only last another two days, in all, only 9 days. Rest well, and warm wishes to the three of you from your Albert 343. From Arnold Sommerfeld Munich, 5 August 1926 Dear Einstein, I was instructed by our committee on guest lectures to kindly invite you to give a few lectures at the beginning of December of this year, one, or better yet, two (perhaps three) for a general audience in the main auditorium, hence probably on the fundamental questions of physics or on natural philosophy furthermore, one especially for physicists on a specific topic. We reimburse the return trip in 2nd class, or a bit more. Furthermore, I ask you please—provided Anschütz does not demand otherwise—to give preference to staying with me in a very modest guest- room. You already gave me your general agreement with this plan last fall. The question is whether you will find the time at the beginning of December. If you only want to give one general lecture, you could perhaps deliver 2 special lectures instead. But these details as well as the particulars about the date lie entirely in your hands! It would be nice if we could spend some more time together again this way. There is much to discuss. You are probably already trying to fit the spinning elec- tron (which is indispensable!)[1] into the gen.[2] theory of relativity, aren’t you?