I N T R O D U C T I O N T O V O L U M E 1 6 l x x v according to which the theory of relativity is an attempt to reduce physics to geometry” (Doc. 97). Einstein’s agreement with Reichenbach hides the fact that they had rather differ- ent opinions on what “geometrizing a physical field” would even mean. For Einstein, the very endeavor was meaningless, whereas for Reichenbach it just was not adding anything new to the physics. Still, Reichenbach believed that giving a geometrical interpretation of a physical field was conceptually worthwhile, and he believed that his own “toy” unified field theory did better in this respect than any of the theories hitherto published by Weyl, Eddington, or Einstein. The reason was that his theory gave a coordinative definition (Zuordnungsregel) for the metric by link- ing it to rods and clocks (as Einstein had in 1915) while also linking the affine con- nection to the behavior of charged particles, or at least electrons, in a similar way.[55] This conception formed part of the background of Reichenbach’s reaction to Einstein’s teleparallel unified field theory, which is based on a space-time geome- try with vanishing curvature but nonvanishing torsion (see sec. V). Despite Einstein’s repeated remarks in correspondence with Reichenbach and in the review of Reichenbach’s book aimed against seeing general relativity or indeed unified field theory as geometrizing physics, Reichenbach interpreted Einstein’s new at- tempt at a unified field theory as wanting to give a new “geometric interpretation” of both gravity and electromagnetism. He wrote: “If one insists that there must be a geometrical interpretation, then I find my approach more beautiful, in which the straightest lines at least mean something” (Doc. 284). In a manuscript attached to the letter, Reichenbach also proposed a classification scheme of how teleparallel geometry, Riemannian geometry, and Weyl geometry relate to one another, a scheme that is a direct rival to the classification scheme Einstein had proposed in Einstein 1928n (Doc. 216). In his answer two days later, Einstein disagreed but tempered the refusal to accept Reichenbach’s schema with a handwritten postscript to the typewritten letter, in which he invited Reichenbach for tea on the following Sunday, pointing out that Erwin Schrödinger, who had just succeeded Max Planck at the Friedrich Wilhelm University in Berlin, would also attend. The information conveyed during informal meetings like this afternoon tea on 21 October 1928, and likely a later one sometime in early 1929, became a matter of dispute and caused a major falling out between Einstein and Reichenbach. On 25 January 1929, the Vossische Zeitung published a column by Reichenbach titled “Einstein’s New Theory” (“Einsteins neue Theorie”). The occasion for the column clearly was Doc. 365, which had already been announced in the daily press, includ- ing the Vossische Zeitung itself, even though the printed paper had not yet been is- sued. Although Reichenbach in no way referred to any specific details of Doc. 365 over and above what was known from the earlier papers of Docs. 216 and 219, the