D O C . 3 9 0 A P R I L 1 9 2 0 3 2 5 We can still discuss the lectures when I have written them. I hope to complete this task this summer.[3] Nothing will come of my trip to England this spring, probably [4] I have already taken upon myself too many obligations for this semester, in particular a university course for foreigners, which keeps me very busy.[5] Letters intended to reach me during the month of May should please be sent to the address of Prof. P. Ehrenfest, Witte Roozen Straat Leyden (Holland). With kind regards, yours. I was born a German[6] in 1879 in Ulm. I spent my youth until the age of 16 in Munich, where I attended secondary school [Gymnasium]. After a brief stay in It- aly I went to Switzerland. Between 1896 and 1900 I studied mathematics and phys- ics in Zurich at the Federal Polytechnic and acquired citizenship of the City of Zu- rich in 1901.[7] From 1902 to 1909 I was employed as an engineer at the Swiss Patent Office in Bern. In 1909 I became Extraordinary Professor at the University of Zurich, in 1911 Full Professor at the German University of Prague. In 1912 I re- ceived a call to the Polytechnic in Zurich to teach theoretical physics. Since Easter 1914 I have been employed in Berlin at the Academy of Sciences with the right, but no obligation, to teach.[8] The dates of my most important scientific ideas are: 1905. Special theory of relativity.[9] Inertia of energy.[10] Law of Brownian motion.[11] Quantum law of the emission and absorption of light.[12] 1907. Basic idea of the general theory of relativity.[13] 1912. Discovery of the non-Euclidean nature of the metric and of its physical constraint by gravitation.[14] 1915. 〈Fundamental〉 Field equations of gravitation.[15] Explanation of the peri- helion motion of Mercury.[16] 390. From Robert W. Lawson [Physics Laboratory, University of Sheffield,] 22 April 1920 Dear Professor, I have finally received the contracts and I send you herewith the ones concerning you. Would you be so good as to add your signature to the contract (above the postage stamp) and then send it back to me?[1] I shall then forward it to Methuen, who will