2 6 2 D O C U M E N T S 2 6 3 , 2 6 4 S E P T E M B E R 1 9 2 8 263. To Horace C. Levinson [Scharbeutz,] 12 September 1928 Dear Mr. Levinson, Your arguments are after all not correct.[1] The reason is simply that the motion of the singularities is determined by the differential equations and cannot be arbitrarily chosen.[2] You indeed have forgotten in your letters that you set (in the second of your equations 11)[3] , which in the presence of singularities does not lead to the equation[4] . Kind regards, A. Einstein 264. To Leo Szilard [Scharbeutz,] 15 September 1928 Dear Patient Sufferer, Through a kind friend, I had the opportunity of giving the A.E.G. a nudge, and not a gentle one.[1] How would it be if you were to sit out your waiting period here, so that you can breathe in a bit of fresh air? In spite of everything, I am looking forward to finishing up our two projects,[2] including the capillary pump, for which I have not yet been able to arouse your enthusiasm.[3] In the meantime hearty greetings, yours truly, A. Einstein My heart is still a bit fluttery. I am reading Spinoza with great pleasure.[4] He understood the freedom of a quiet place in the country. A 4    4 t r c  –   d r ------------------------------ = A 4   x  - 1 3 -----------  4   x  -----------     d  r ------------------------------ =