The existence of relatively consistent non-Euclidean geometries leads him to the view that geometric propositions cannot be determined by a priori intuitions and that it is necessary to study “the structural relations between Euclidean and non-Euclidean geometry” (Nye 1979: 111). Poincaré established a famous dictionary translating concepts and propositions of Lobachevskii’s geometry into Euclidean geometry in order to create a model to show the relative consistency of Lobachevskii’s geometry (P