 In the decade or so following the appearance of the general theory of relativity, there was much talk of a reduction of physics to geometry (e.g., Hilbert 1917; Weyl 1918b, 1919; Haas 1920; Lodge 1921). While these discussions were largely, and understandably, confined to scientific circles, they nonetheless brought distinctly philosophical issues—of methodology, but also of epistemology and metaphysics—together with technical matters. Einstein’s mathematical representation of gravitational field potentials by the metric tensor \(g_{\mu\nu}\) of a variably curved spacetime geometry was quickly termed a “geometrization of gravitational force”. Weyl and others acclaimed Einstein as reviving a geometrizing tendency essentially dormant within physics since the 17th century. In so doing, Einstein supposedly opened up the prospect of a complete geometrization of physical theory, the possibility of finding a unifying representation of all of known physical interactions within the frame of a unique metrical theory of the four-dimensional spacetime continuum. Einstein himself, as will be seen, turned out to be highly critical of the idea of “geometrizing physics” even as the general theory of relativity was its inspiration. This was certainly the case for the Göttingen mathematician David Hilbert (1915, 1917). In the very week in late November 1915 when Einstein presented his completed gravitational theory to the Berlin Academy (on Thursday), Hilbert (the previous Monday) proposed to the Göttingen Academy a schematic generally covariant axiomatization coupling Einstein’s gravitational theory with a relativistic electromagnetic theory of matter due to German physicist Gustav Mie. Hilbert’s theory could not possibly succeed (however, that matter is not fundamentally electromagnetic in nature was only shown in the 1930s by the quantum physics of the atomic nucleus). It is remembered today mostly for the so-called “Einstein-Hilbert action” in the usual variational formulation of Einstein’s theory. But at the time Hilbert viewed his theory as a triumph of his “axiomatic method” as well as a demonstration that