D O C . 1 6 6 N O V E M B E R 1 9 1 9 1 3 9 the suspended spheres surprised me very much it is a paradoxical matter.[4] I will lay out in detail my position on the ether question as soon as the occasion presents itself. I would have been more accurate in my earlier publications if I had limited myself to emphasizing the nonreality of the ether’s velocity rather than the nonex- istence of the ether in general. For I see that with the very word “ether” one is say- ing no more than that space must be conceived as a carrier of physical properties. I see another thing, too. My view that the state of the ether (i.e., the ’s) must be determined entirely by the matter alone has nothing compelling about it. That is why one cannot argue for the closure of the world with as much certainty as I have done.[5] Nevertheless, I do not abandon the hope that astronomical experience will permit an answer to this question, although we may not live to see it. Perhaps it will come out of an analysis of the Milky Way I am currently making efforts along this line.[6] Using Newton’s diction, the problem can also be posed like this: Do force lines of gravitation end in empty space, or is Gauss’s law strictly valid also for the largest spaces accessible to our experience? I must admit, though, that the alterna- tive of a spatially closed world seems much more likely to me, since I consider it unlikely that the density limit would vanish for ponderable matter. I carefully went through the majority of your lectures and relished doing so greatly. The description of radiation theory (esp. of Wien’s displacement law, Kirchhoff’s laws) and the newest advances in quantum theory appealed to me par- ticularly.[7] With cordial regards to you and your wife,[8] and many thanks to both of you for your hospitality, I am devotedly yours, A. Einstein. I forgot to express my special thanks to you for admission into the Batavian Soci- ety, which pleased me so much a few months ago and which I owe to you.[9] To my great joy I heard that de Haas is feeling well again. I ask you please to relay to them both my affectionate greetings.[10] 166. To Mileva Einstein-Maric [Berlin,] 16 November 1919 Dear Mileva, Your complaint regarding the 2000 marks is completely justified. I received the money as an erroneous deposit but shall make sure that you receive a certificate of equal value (or the money) on your account after it has been opened in the Zurich Kantonalbank, in accordance with your wish.[1] I had always wondered where the gμν