4 5 8 D O C U M E N T 5 3 3 M A Y 1 9 2 9 533. Elsa Einstein to Paul Ehrenfest [Berlin,] 21 May  Dear Mr. Ehrenfest, Albert is at the Solvay Congress in Brussels. In his opinion, it was absolutely necessary that he participate in it. Even though he was in outstanding health, I was very reluctant to let him go. He is not used to taking care of himself, and something could easily happen there that would harm him. A trip to Holland is out of the ques- tion, good Mr. Ehrenfest. That would be something that he cares about, that he loves. But it would be a crime if he were to do it. He is not supposed to give any lectures, none at all. That would involve tension along with agitation. All these things must be strictly avoided, so that he can continue his scientific work as peace- fully and intensively as he has been able to do so splendidly this past year. In Brussels he is not speaking in November he has to pick up the honorary doctorate in Paris! That also frightens me. I still don’t know how one can keep him from doing harm to his health from that. But he can’t avoid Paris if he is given this honor. And a stress is connected with that and it is not good for him.— Ilse is not well. Nothing at all can be done for her, either, after the unfortunate failed operation. I wrote that far at the time. Then I came across this letter. It got drowned in the heap of paper that piles up in our home every day. I didn’t look for it. I was so sloppy and wrote nothing more. Felt guilty about it. What a remarkable mixture we humans are! I should have taken another sheet of paper and written you again. That would have been much simpler. Instead, I tormented myself with guilt. In the meantime, your wife came to see us. She is so joyously alive and magnificent. I like her a lot. And even though I am so pitifully primitive intellectually (compared with her), I nonetheless get along splendidly with her. The day after tomorrow Hedi Born is coming to visit us for a week. There is a very intimate relationship be- tween Margot and her. Hedi has probably struggled with herself recently, and Born has also been through difficult times. Such a marriage is a very complicated matter! Warm regards, your Elsa Einstein Postscript. Don’t worry, this letter was begun on 21 May and finished today, 11 June! This kind of thing must never happen again! Let your wife report to you about how much they like Tanischka in Göttingen, how splendidly she assists Born with the work.