4 4 4 D O C U M E N T 4 5 0 J A N U A R Y 1 9 2 7 because they do not behave, for the moment, according to my wishes. I hope that you can understand me in that. In my opinion, an interesting job with the least pos- sible pay and as far as possible from here and good social relationships would be the best & most beneficial thing for Albert. Now you will see what you can do with him. I’m not very optimistic. Tete is do- ing better now [9] he wrote you an amusing letter yesterday from which you will see that he is again the jolly fellow, as always. He absolutely did not want to wait to send the letter until I had also written. I received Elsa’s[10] letter in the meantime I’m thankful for it. For today, another friendly greeting! Mileva Please write me when Albert is there at your place, how you think he’s doing. 450. To Paul Ehrenfest [Berlin,] 11 January 1927 Dear Ehrenfest, You people really are touching! Of course I’m glad if I can stay connected with the University of Leyden in such a way, without the obligation, which is so difficult for me to fulfill.[1] The salary can officially remain as it is. In reality, though, I’ll hand the sum over to you and Voltjer, for instance.[2] Then, if I do come, I can be reimbursed for my travel and stay. If I don’t come, both of you can spend the money to benefit the Institute or young physicists you will welcome that, and the curators of the University Fund will also find it appropriate. I convey my warmhearted thanks to those involved for their great generosity. I’m happy that you found something nice and am curious. The problem of mo- tion turned out fine, although there is still a small hitch in it. In any event, it is in- teresting that the field equations can determine the motion of singularities.[3] I even think that this is going to define the development of quantum theory again, but the path there is not yet discernible. My heart doesn’t warm to this Schrödingerism— it’s non-causal and generally too primitive. Masses simply do exist, I won’t let go of that. I don’t believe that kinematics must be abandoned.[4] Warm regards to you and your young folk from your Einstein Ah, yes, I almost forgot about the gas. It’s all the same to me whether or not you regard the molecules in the lowest quan- tum state as a special phase. The Boltzmann quantum distribution law and even Maxwell’s vel[ocity] distr[ibution][5] can be defined thermodynamically in such a