Secondly, while ‘existence’ of the objects is just a matter (as Zermelo says) of belonging to the domain (a fact which is established by the axioms or by proofs from those axioms), the mathematical existence of the domain itself, and (correspondingly) of the system set out by the axioms, is established only by a consistency proof for the axioms. Thus, to take the prime example, the ‘existence’ of Euclidean geometry (or more accurately Euclidean geometries) is shown by the consistency proofs given by means of analytic   geometry.[9]  Thus, the unit of consistency is not the concept nor the individual propositions, but rather the system of axioms as a whole, and different systems necessarily give accounts of different primitives. The expectation is that when a domain is axiomatised, attention will turn (at some point) to a consistency proof, and this will deal finally with the question of mathematical existence. In any case, the task of showing existence is a mathematical one and there is no further ontological or metaphysical mystery to be solved once the axioms are laid down.