4 0 D O C U M E N T S 2 0 , 2 1 J A N U A R Y 1 9 2 2 winds, op. 16, would be very appropriate for Hilbert: it is easy to grasp, very melo- dious, and not difficult to play, either. You would be entirely free to decide whether to play violin or viola instruments of adequate quality are also here. I think that Hilbert would be particularly pleased if you wanted to be a part of this little sere- nade just the few guests invited to the midday meal will be listening but every- thing concerning the timing and the piece could be rearranged according to your wishes. I would be very grateful if you would inform me briefly on a postcard whether you say yes or no we could then settle the rest here with Born so that you are very little inconvenienced by rehearsals, etc. Incidentally, Edwin Fischer gave us the idea to ask you to join he was here recently and told us about his music-making with you.[4] With most cordial regards, yours very sincerely, R. Courant. 20. From Michael Polányi[1] Berlin, 15 January 1922 Esteemed Professor, I went over the calculations again and discovered an error caused by a misprint in Füchtbauer’s paper.[2] There a “2” is indicated where a “λ” should stand. Thus the contradiction is solved and one arrives at the thermodynamically required rela- tion between the decay time and the absorption coefficient.[3] – It also seems to me that if quantum effects of the kind sought do exist in gases, they cannot in any case become perceptible in the emission process of individual atoms. In great respect, sincerely yours, M. Polanyi 21. From Sanehiko Yamamoto[1] [Tokyo, 15 January 1922] The negotiations. Kaizosha has the honor of most courteously inviting Professor Dr. Albert Einstein to Japan and asking him to give some lectures. We are both agreed about definitely satisfying the following commitment: