The method of classification adopted for numbers may be applied to
sizes, and thus distinguish the line, the surface, and the solid or
body, because those are sizes which form different species. If besides
each of these species were to be divided, lines might be subdivided
into straight, curved and spiral; surfaces into straight and curved;
solids into round or polyhedral bodies. Further, as geometers do, may
come the triangle, the quadrilateral, and others.