D O C U M E N T 3 0 2 J U N E 1 9 2 6 3 1 9 302. From Paul Ehrenfest Leyden 8 June 1926 Dear Einstein, A totally totally huge request of you: Lorentz, Zeemann, Fokker,[1] and I, as cu- rators of the Lorentz Fund, have invited Oskar Klein[2] (cf. “Rosseland-Klein”[3] ) to Leyden for about 4 weeks in order to hear as much as possible about the VERY great things he has done in the same direction as Schrödinger[4] (not yet published).[5] He has been here a few days and we are enjoying him very much as a person (a totally wonderful dear fine man) and his ideas.— And now we lack only one thing, namely, your presence!!!!— My request: Please come visit us in Leyden before the end of June. Possibly even for a shorter time than usual if it is otherwise too burdensome.— Although you, of course, know that we are all the more pleased with each additional day! Ceteris paribus,[6] I would ask you to arrange things so that your stay here in any case includes the LAST FEW days of June! Dear Einstein! I have hesitated for a long time to burden you with this request. However, for Klein himself and for all of us here it would be so incredibly import- ant if you wanted to encourage these great things in statu nascendi.[7] — I know with absolute certainty that you will immediately become very fond of Klein, a fa- vorite student of Bohr’s,[8] and that the group of young people who are currently gathered will be particularly to your liking! You will have to give no lectures whatsoever! Also, absolutely no “shop talk”! I also request very very strongly that your wife support my request of you.[9] Delight us all with a very quick yes![10] Warm regards, your I ask you to reply to Coster[11] whatever you consider appropriate