“It has long been the custom in the schools as well as the university, first to study the plane and then, entirely separated from it, the geometry of space. On this account space perception, which we possess originally, is stunted. In contrast to this the 'fusionists' wish to treat the plane and space together, in order not to restrict our thinking artificially to two dimensions.....”Felix Klein
Assiomatica: da 1D a 2D 3D tramite il prodotto cartesiano.
Cognitiva: da 3D a 2D 1D 0D.