  Schlick availed himself of the opportunity to elaborate his epistemological views in application to the new physics of Relativity in his 1915 essay on “The Philosophical Significance of the Principle of Relativity” (1979a, 153–189). This essay is particularly significant in Schlick’s development since it first presented certain philosophical tenets which would figure in all his subsequent work. Implicit in the general philosophical scheme in which Schlick discussed Relativity is an objective, logical distinction between the representational framework in which scientific claims may be formulated and those claims themselves. An intrinsic function of the representational scheme is the constitution of the very concepts in which the formulation of empirical claims is first made possible. Moreover, since the same empirical claims may be expressed in distinct representational schemes, the content which is expressed by all the differing conceptual frameworks comprises the common, objective content of scientific assertions. In contrast, what varies from one description to another reflects the features of the representational systems which distinguish them from one another.