7 8 D O C U M E N T S 6 9 – 7 1 S E P T E M B E R 1 9 2 5 69. Verse for Kuno Kocherthaler?[1] [Berlin, after 16 September 1925][2] A dweller of Madrid in exile Hankers after the paternal domicile. 70. To Hugo A. Krüss [Berlin,] 17 September 1925 Dear Prof. Krüss, Koppel really got his hackles up when I presented the proposal to him.[1] He complained about managerial obstacles. Then he composed himself and proceeded to counterattack. The plan for the books now seemed ineffective to him. In contrast, he liked the plan of reciprocal invitations of deserving scholars. The books could be obtained gratis from the publishers. He would be willing, along with some 9 others (clever decimal system), who are yet to be found, to assume the obligation to bear the costs arising from the invitations, envisaging that the expenses accruing to each one would be on the order of 5000 M. He believed a committee that would report on the steps to be taken should be formed immediately. So much for Koppel. I would add nothing but the hope that something can occur that is perceived by the French as a gracious gesture. They did not play any “pres- tige politics” in this case, and it would be very nice if this aspect along with our reaction to their move could be put way into the background. Kind regards, sincerely yours, A. Einstein 71. To Paul Ehrenfest [Berlin,] 18 September 1925[1] Dear Ehrenfest, I am very pleased to spend time together with Bohr in December.[2] I gladly grant you all isolation authority. As regards the time, I think that I would like to stay with you for a good fortnight, and I leave it to you to choose the time. I can arrange it as I please, you know. I’m not thinking about experiments at the waves/