  In correspondence with Einstein, Schlick explained that his monograph on Space and Time in Contemporary Physics was “less a representation of the general theory itself than a thorough-going elucidation of the thesis that space and time have now forfeited all objectivity in physics” (Schlick 1917). Of course, Schlick is referring to Einstein’s remark in his 1916 paper on the General Theory, that the admission of arbitrary coordinative transformations “removes the last vestige of physical objectivity from space and time” (Einstein 1916, 117). In his monograph, Schlick first described the differences between the space of the older physics and the space postulated by Einstein. In Newtonian physics (as well as the physics of the Special Theory), all measurement was founded on the notion of a rigid rod and space was still regarded as Euclidean so long as measurements were made within the same coordinate system. Thus, in the older physics, space was conceived as complete with metrical properties, defined by rigid rods which possess the same length in any place at any time. It is particularly to be noted that the metrical properties of space were regarded as independent of the distribution of bodies in space and their gravitational fields. It is precisely these conditions that are changed in General Relativity. Rather, in the General Theory, the principle of general covariance implies that properties cannot be ascribed to space independently of any consideration of the things in it. Einstein showed that non-Euclidean methods of determining measurements must be used in the presence of a gravitational field and this follows from the insight that it is the things in space which give it a particular structure. The result is a complete relativization of space (Schlick 2006a, Sec. VII). 