2 0 V O L . 7 , D O C U M E N T S 5 0 a , 5 6 a Vol. 7, 50a. On the Present Situation in Theoretical Physics [Vienna, 14 January 1921][1] If I survey the present situation in theoretical physics, I find one point of the greatest importance that is not taken into account sufficiently. A theoretical system can only claim completeness when the relations between the concepts and the facts of experience are unambiguously established. It does not suffice, for example, to base the theory of relativity only on a fundamental mathematical invariant. It also has to be clear how this invariant relates to the observable data, as has hap- pened with the fundamental concepts of Maxwellian theory through Heinrich Hertz. If this aspect is left out of consideration, one can only arrive at unrealistic sys- tems. Vol. 7, 52a. Opinion on Eggeling and Richter’s Project Berlin W. 30, 3 February 1921 Haberlandstr. 5 [Not selected for translation.] Vol. 7, 56a. “International Relations in Science” [2 April–10 August 1921?][1] ... In this agitated time of strife among nations and the social strata, one of the most precious goods of humanity seems to be under threat: the internationality of science.[2] Scholarly organizations in the individual countries have allowed them- selves to be carried away by nationalistic passions to the point that they rival polit- ical bodies in the political contest so much did they forget that they are made to foster and preserve endeavors that must stand high above all political struggles among people ... I believe the most important thing is to awaken in the younger gen- eration a strong love for scientific truth and ambitions, so that the purer atmosphere thus created will gradually drown out the insensitive emotional motives that have brought so much misfortune upon our current generation ...