3 2 0 D O C S . 3 8 4 , 3 8 5 A P R I L 1 9 2 0 384. From Federigo Enriques[1] [Bologna, 9 Gozzadini Avenue, 20 April 1920][2] Dear and illustrious Colleague, Professor Zangger’s postcard, which bears also your signature, offers me the pleasant opportunity of conveying my deep gratitude for your interest in my re- search on the theory of science, which you have expressed many times over the years, and in particular, of responding to a postcard that I received at the beginning of this inauspicious war, and to which for this reason I could not reply. The approval and the esteem of a superior spirit like yours are one of the most desirable prizes to which my work could aspire. Not just to reciprocate your cour- tesy, but to express a sincere feeling, I will tell you that I have followed your bril- liant scientific career since the beginning: already in 1904 certain distinguished friends in Paris (such as Perrin) were speaking of you with the greatest en- thusiasm.[3] I am now of course aware of what everyone knows, that is, of your lat- est great success, whereby you have succeeded in taking an essential step over the Newtonian theory [4] nevertheless, I could not say that I have fully assimilated the spirit of its organizing principles, to which, I am convinced, there must be more than the mathematical formulas. It is my heartfelt desire to meet you in a setting favorable to a leisurely conver- sation. Who knows when I shall be able to satisfy this wish? In the meantime, il- lustrious Colleague, please accept the expression[5] of my warm and devoted re- gards, yours, Federigo Enriques. 385. From Richard von Schubert-Soldern[1] Zwettl, Lower Austria, 13 Franz Josef Place, 20 April 1920 Highly esteemed Professor, Perhaps you still remember me because of a work on the relativity of time [Rel- ativität der Zeit], which I had sent you for evaluation. It was then later published at the time of the collapse in Austria in the Archiv für system. Philosophie with the addition you wanted, and it is to be hoped that you received a copy of it.[2] If I ap- proach you again it is unfortunately on a personal matter. To this end I would like