I N T R O D U C T I O N T O V O L U M E 1 4 l i x that he was now “beginning to understand the enormous suggestive impact that has emanated and still is emanating from this fellow.” However, he quickly went on to say that he had to “tone down the ‘a priori’ into ‘conventional’ in order not to have to contradict Kant, but even then it does not fit in the details” (Einstein to Max Born, 29 June 1918 [Vol. 8, Doc. 575]). In his review of Elsbach’s book, Einstein began by opting for realism as the belief in a mind-independent world, alongside the demand for trust in the reliability of our senses that tell us, at least indirectly, about what is real. After noting that con- ventionalism was not sufficiently addressed by Elsbach, and that he who does not define a priori concepts as unchanging should not consider himself a Kantian, Ein- stein granted that for every system in physics it is possible to denote some concepts consistent with said system as “a priori.” But, he continued, since the overall sys- tem refers to reality only as a whole, the split between empirical and allegedly a priori concepts is in each case an arbitrary one. In his review of Josef Winternitz’s book on Relativity Theory and Epistemology, which also advocated holism, Einstein, firmly convinced that there are no unchang- ing a priori concepts, renamed these as “conventions” (Einstein 1924a [Doc. 149]). Thus, for Einstein, a holistic view of how concepts refer to the world, a negation of Kant’s unchanging a priori, and opting for renaming allegedly a priori statements as conventions, were views that supported each other.[28] Einstein used his criticism of Kantianism as a launching pad to reiterate two pos- sible positions with regard to geometry that he had already outlined in the 1921 lec- ture on Geometry and Experience (Vol. 7, Doc. 52). However, while the discussion in the latter document was situated in the context of either choosing conventionally or determining empirically the Euclidean or non-Euclidean geometry of space, respectively, in his review of Elsbach he argued more generally:[29] either we accept practically rigid bodies as existing in nature, and can then determine the geometry of space empirically (“standpoint A”), or we deny that practically rigid bodies exist, and then take geometrical facts and physical laws as a holistic whole that only jointly refers to nature, and in which the split between empirical and con- ventional elements is itself arbitrary (“standpoint B”). Einstein concluded that, whichever standpoint one takes, the neo-Kantian attempt to reconcile Kant and rel- ativity theory by arguing that they speak of intuitive space and empirical space, respectively, is doomed to fail. However, in his popular exposition on non-Euclidean geometry and physics, Einstein 1925g (Doc. 220), just like earlier in Vol. 7, Doc. 52, Einstein claimed that standpoint A (which he now identified with Helmholtz) was “better suited to the present state of our knowledge” than standpoint B, identified with Henri Poincaré. And yet, in his Nobel lecture (Doc. 75) a year earlier, he had emphasized even more