Natural language occurs throughout mathematics to set the mathematical activity in context. In the visuo-spatial to verbal developm ent, natural language becomes a vehicle for describing iconic images and formulating proof. It can also be used to describe properties of numbers, for instance, that addition is commutative because it is observed to be always independent of the order (a fact easier seen by visualising the change in order than carrying out the counting procedure—a valuable use of the interrelations between visual and symbolic.) Meanwhile the “artificial language of number” has mental objects which are procepts and the “artificial language of logic” in advanced mathematics has concepts which are formally defined.