1 5 2 D O C U M E N T 1 6 7 A P R I L 1 9 2 2 all professors at the Collège de France are like your friends. Read the pamphlet by Professor Georges Blondel, “The Disappointments of Peace and the German Peril” [Les mécomptes de la paix et le péril allemand] and you will understand me. I have been working here for two years as best I can toward an alleviation of the tension. It was only for this purpose that I gave in to my friend Theodor Wolff’s wish, left my home and my books in Berlin, endured the semiannual separation from my wife (Rosa Bertens), and took up the effort and struggle again on this hot soil, instead of my comfortable employment in Berlin. I do not want to com- plain personally. Most of my friends remained loyal to me and the opponents at least know that I tell the truth and am well intentioned. But the press and the cham- ber are hopeless at the moment. Here in Paris I learned to love my homeland more honestly, despite all its faults. Nevertheless, one should not lose hope. Your appearance in Paris was a very fine thing. A glimpse into the future perhaps an avenue into the future. I wish I could live to see it. With obliging regards and in great respect, yours, Paul Block. 167. From Paul Langevin Paris, 25 April 1922 My dear Friend, I was happy to know that your return proceeded without incident and that you are going to be able to take a well-deserved rest in the knowledge of having per- formed, from all points of view, useful service. The too short days you spent here will remain with me as happy days. Like you, I regret that we did not have the time to chat at leisure and, that this pleasure must be postponed until your next visit, which I hope will in fact be soon. I just expedited to Mr. Kocherthaler a check representing the amount you left with me. Certain measures were required to obtain the necessary authorization and for this reason the remittance took place a little late. I asked our correspondent to acknowledge receipt to you directly. Please find in attachment a word by Mr. d’Ocagne, member of the institute and a distinguished mathematician. He followed our discussions and knows their topic well. See if you can gratify him.