In this solution of the question it is not easy to see how the material principle, which, by its alliance with quantity, individuates the form, is itself individuated so as to be the source and principle of a multiplicity of numerically distinct and incommunicable realizations of this form. Perhaps the most that can be said on this point is that we must conceive quantity, which is the fundamental property of corporeal reality, as being itself essentially divisible, and the material principle as deriving from its essential relation to quantity its function of multiplying the same specific nature numerically. Of those who reject the Thomistic doctrine some few contend that it is the _actual existence_ of any specific nature that should be conceived as individuating the latter. No doubt the universal as such cannot exist; reality in order to exist actually must be individual. Yet it cannot be actual existence that individuates it. We must conceive it as individual before conceiving it as actually existent; and we can conceive it as individual while abstracting from its existence. We can think, for instance, of purely possible individual men, or angels, as numerically or individually distinct from one another. Moreover, what individuates the nature must be essential to the latter, but actual existence is not essential to any finite nature. Hence actual existence cannot be the principle of individuation.(149) Can it be contended that _possible_ existence is what individuates reality? No; for possible existence is nothing more than intrinsic capacity to exist actually, and this is essential to all reality: it is the criterion whereby we distinguish real being from logical being; but real being, as such, is indifferent to universality or individuality; as far as the simple concept of real being is concerned the latter may be either universal or individual; the concept abstracts equally from either condition of being.