D O C U M E N T 6 3 F E B R U A R Y 1 9 2 2 8 1 63. To Paul Langevin 27 February 1922 Dear friend Langevin, When I received your kind letter of invitation,[1] I felt great and pure joy and now, one week later, I hesitantly and sadly take up my pen because I cannot accept the invitation now, as much as I would personally have liked to—even aside from the cordial feelings of friendship I have for you. You know that I am of the view that relations between scholars should not suffer from political causes and that con- cern for the scientific professional community should go above all other consider- ations. You also know that I am totally internationally minded and the fact that I am employed by the Prussian Academy of Sciences has had no influence on this mentality.[2] After conscientious reflection, however, I came to the conclusion that at this moment of political tension my visit to Paris would have more adverse than favorable consequences.[3] My colleagues here are still being excluded from all international scientific activities and they are of the opinion that our fellow French professionals are primarily to blame for this.[4] I fully appreciate the deeper causes that led to this attitude. But on the other hand you, too, can imagine that these peo- ple here, whose sensitivities have been stirred up almost to pathological heights by the events and experiences of the last few years, would perceive a trip by me to Paris at this moment as an act of betrayal and would take such offense that very unpleasant consequences could arise. Even in Paris, unforeseeable complications threaten. I cannot imagine anything finer than being able to chat comfortably with you, Perrin, and Madame Curie again in private and to depict the theory of relativity to your students with a subjective brush.[5] Yet the greater public and—politics— have long since taken possession of my theory and my person and have tried to make both somehow suit their purposes. There would be a considerable number of people watching out for every candid word I utter, to toss it back at newspaper read- ers, conveniently repackaged.[6] My experiences in this regard in recent times make this danger appear to me to be very great the end effect is always hatred and ani- mosity instead of reason and goodwill.[7] I would certainly also be interrogated about my political opinions regarding Franco-German relations as I cannot speak any other way than honestly, my reply would not earn me sympathy either on this side of the Rhine or on the other. It is true that I did not hesitate to visit North America, England, and Italy in the past few years. However, my American voyage concerned the University of