2 5 4 D O C U M E N T S 2 5 8 , 2 5 9 A U G U S T 1 9 2 8 258. To Chaim Herman Müntz [Scharbeutz,] 22 August 1928 Dear Mr. Müntz,[1] Your electron is possible, if one takes as the Hamilton function: .[2] Then the invariant comes into its own.[3] Now, one will have to search for the law of motion for the singularities,[4] so that one can see if it is in any way jus- tified to identify the with the el.[ectric] potentials. I developed the method in the earlier theory of gravitation in such a way[5] that it can be readily applied to other cases. I look forward to showing you all that. Kind regards, your A. E. 259. To Paul Ehrenfest [Scharbeutz,] before 24 August 1928][1] Dear Ehrenfest, I was terribly tickled by your note, which showed great liveliness, and also pleased by the greetings from Busch and Serkin.[2] Hopefully you are now back home again, so that you can satisfy the money-hunger of my old age—I think by a check in Guilders or a registered letter.[3] We have now been for months on the Bal- tic, where my vital spirits are slowly gaining strength. At the same time, I’ve seen for the first time what a stupid life people lead in the city, and how happy one can be in quiet and seclusion. It’s splendid for thinking, too. I have now mastered the problem of movement for singularities to the point that I can apply the method to any field theory.[4] I believe less than ever in the essen- tially statistical nature of the event, and I have decided to use what little strength for work that remains to me in accord with my own interests, independently of cur- rent preoccupations.[5] Unfortunately, I must close, because the mail carrier is coming. Warm regards to all from your Einstein H hg                 –  =       