9 4 D O C . 1 0 9 S E P T E M B E R 1 9 1 9 109. From Paul Ehrenfest [Leyden,] 21 September 1919 Dear Einstein, Your letter made me blush with pride, even though it draws a bold line through my calculations. And everyone who is fond of you here surely feels exactly the same way![1] — • — Right upon receiving your letter I went to purgatory: 1. Because it suddenly became clear to me that the fluctuating valuta should not be able to give people the right to reach into other people’s souls.—[2] 2. Because I would in any case have been obliged to gain complete confidence about the practicability of my dreams before I should have dared to rattle you about it.—The added enthusiastic approval by two men who can assess the practical side of the problem perhaps made me a bit incautious about that.[3] In addition to this was the fear of simply coming too late!– But you will forgive me for both sins. — • — Following your letter, I am in complete agreement with you.—Yet it seems con- ceivable beyond a doubt to me that a way could be arranged for you to be able to offer Leyden something without being disloyal to Berlin.[4] I have already started to fantasize about that with my junior friends. But I want to save that for your visit with us, so as not to worry you again before I have anything firm in hand. — • — Now to your visit with us!! Most preferable would be for me if you came about October 15th. For I am greatly concerned about whether in the later, colder season I can guarantee you a room that is simultaneously quiet and well heated. [We don’t have any coal for the central heating and only 3 ½ rooms of the whole house are heated!—But from 15 Oct. to 15 Nov. there’s no danger yet of that].[5] It is already arranged that you won’t incur any costs whatsoever for the trip and the stay. You might help just a little in bringing it up to round figures, though, by presenting a talk to a sympathetic audience about something simple (e.g., with little philosoph- ical nuances). However, that is not necessary, in case you find it tedious !!!![6] On the occasion of your sojourn (which may not under any condition be shorter than a fortnight!!) I hope to acquaint you with an old country-seat of the finest type in Dutch culture. You will take back very precious and warm memories with you from there.[7] — • —