 But Frege wanted more than just a logically powerful enough source for arithmetic; he wanted, in addition, a principle that would account for the metaphysical nature of numbers. They must, surely, at least be abstract? Numbers are also eternal and necessary. They are not located in space, and they do not enter into any causal interactions. Frege therefore sought a deeper logical theory that might be able to vouchsafe for numbers these latter characteristics, and thereby solve the Caesar Problem. 