 As Poincaré explains in a section entitled “Form and Matter” of his Monist article of 1898, the idea is that in geometry the properties of the primitives or of the objects to which geometrical relations are applied are not important at all, as far as geometry is concerned. The set of relations that hold between the primitives constitute the form, not the matter, of geometric objects, and these relations are what are studied. The form constitutes the relational aspect of Poincaré’s structuralism.