D O C U M E N T S 2 6 3 , 2 6 4 A P R I L 1 9 2 6 2 7 7 263. From Hermann Anschütz-Kaempfe Munich, Leopoldstrasse 6, 23 April 1926 Esteemed, dear Prof. Einstein, I have a rough time behind me 5 weeks ago I fell with my horse & broke my collarbone and 3 ribs & then I got a straitjacket & that was very unpleasant. But now I am again relatively mended and am on the verge of checking on Kiel again to see what all is going on there.[1] However, won’t be able to stay there long. I think I’ll be there by the middle of next week but have to leave again after a one- week stay since I have an important meeting here. It would be very nice of you if you would check again how things look in your apartment & whether the Bommi is ready to sail,[2] & to sit at the fireplace and to be able to chat with you would also be very nice. I’ve heard nothing more at all from Albert I still think he is pigheadedly running into an impossible situation [3] I also think it was unwise for you to present him with an alternative so difficult to endure [4] perhaps he is bucking again & will be rescued on the other side. With best wishes to you & your wife[5] from yours truly, Anschütz 264. From Erwin Schrödinger Zurich, 23 April 1926 Dear Professor, I thank you very cordially for your extremely kind letter of the 16th.[1] Approval by you and Planck[2] is more valuable to me than approval by half the world. Be- sides, this whole matter would certainly not have arisen now, and perhaps not at all (I mean, not on my part), if your second gas degeneracy paper[3] had not shoved the importance of De Broglie’s ideas in front of my nose. The objection in your last letter makes me even happier. It is based on a memory slip.[4] The equation in fact is not mine my equation does indeed read verbatim exactly as you construct it freehand out of the two requirements of the “additivity” of the quantum levels and of the impermissible occurrence of the absolute value of the energy: div gradϕ E2 h2( E Φ) – ------------------------ϕ + 0 =