ALS in German, signed “A. Einstein,” one page, 3.5 x 5.5, postcard letterhead, April 1926. Letter to Hans Reichenbach in Stuttgart, Germany, concerning Reichenbach's recent work on geometrization of the magnetic field as well as his criticism of Hermann Weyl's similar theory. In full (translated): "You are absolutely right. It would be incorrect to assume that 'Geometrization' is something fundamental. It is nothing more than a donkey's bridge for discovering numerical laws. Considering this a theory for 'geometric' representation would be just an inconsequential matter of personal preference. Fundamentally new is that Weyl, by subjecting the transformation formula in addition to invariance to a new requirement, namely the ('calibration invariant'). However, this advantage is neutralized because switching to equations of the fourth order will be necessary, which in turn means a substantial increase of the arbitrary factor…If there is anything I can do for you, do let me know." In fine condition, with two file holes affecting none of the text.At the time of this letter, Reichenbach and Einstein were communicating about the former's construction of a theory establishing a connection between electricity and geometry, which he hoped would prove as effective as that of general relativity connecting gravitation and geometry. Reichenbach concluded, however, that his theory was less successful than that of general relativity, and he informed Einstein in a prior letter that based on his experiments, evidence proved that geometrization of a physical field cannot be considered a significant advancement. In this letter, Einstein appears to agree with Reichenbach, while at the same time criticizing Hermann Weyl's own theory on geometrization of the electromagnetic field.Format: ALS