  Weyl was very critical of Einstein’s attempt to incorporate version  (2) of Mach’s Principle into the theory of general relativity and  relativistic cosmology because he considered the Leibnizian-Machian  relational conception of motion—according to which all motion is to be interpreted as the motion of some bodies in relation  to other bodies—to be an incoherent notion within the context  of the general theory of relativity. 