2 1 4 D O C . 2 5 6 J A N U A R Y 1 9 2 0 again after so many years, a fortunate choice in assuming the role as seat of the League of Nations.[2] Your analysis on electron motion counts, in my view, among the most important verifications of the special theory of relativity.[3] I do not recall whether I expressed my joy to you, at the time, about the success of this fine experiment. In happy anticipation of seeing you and our other Genevan colleagues soon, I am with cordial regards, yours. 256. To Hendrik A. Lorentz [Berlin,] 12 January 1920 Highly esteemed and dear Prof. Lorentz, I was shocked to discover today that you have had to wait for an answer to your generous offer of December 21st,[1] which I still have not sent to you. I accept the same with a feeling of sincere gratitude and consider myself fortunate to be seeing you and your nice colleagues there again regularly in this way. My only concern is the consideration that it won’t be at all easy for me to offer Leyden students any- thing that they do not acquire in a far more comprehensive form from lectures by you, Ehrenfest, etc.[2] It might be able to work, however, if you tell me what I should lecture on. I shall adjust myself with pleasure in accordance with the need. I shall hold the inaugural lecture you mentioned on the ether. It is a fine opportunity to make the clarification you suggested.[3] — The new publication about Lille is in print and has already been the object of strong animosity. You shall receive a copy very soon. It is sad that even highly ed- ucated people cannot extricate themselves at all from the illiberal nationalistic standpoint, not even when it comes down to right and wrong.[4] The evil of the past lives on and on, with no end in sight. We are going through a sad time owing to the desperate illness of my poor moth- er. Let’s hope she will be relieved of her sufferings in the foreseeable future.[5] Now the redshift of spectrum lines of the Sun has also been established with quite good certainty by Grebe and Bachem in Bonn. The previous negative result is simply explained in that, in identifying the solar lines with terrestrial lines 〈owing to〉 while disregarding the abundance of surrounding lines in the solar spectrum, they proceeded as if no shift had to be taken into consideration from this, system- atic errors arose. The paper will appear soon.[6] However, this settlement is still not