------------------ [2] See the Sophista of Plato, where this is asserted.

[3] For a thing cannot be said to be a principle or cause without the subsistence of the things of which it is the principle or cause. Hence, so far as it is a principle or cause, it will be indigent of the subsistence of these. ------------------

Introduction to the Philosophy and Writings of Plato — Part 7

Further still, the simple subsists according to a transcendency of other things, the most powerful according to power with relation to the subjects of it; and the good, the desirable, and the preserving, are so called with reference to things benefitted, preserved, and desiring. And if it should be said to be all things according to the preassumption of all things in itself, it will indeed be said to be so according to the one alone, and will at the same time be the one cause of all things prior to all, and will be thus, and no other according to the one. So far, therefore, as it is the one alone, it will be unindigent; but so far as unindigent, it will be the first principle, and stable root of all principles. So far, however, as it is the principle and the first cause of all things, and is pre-established as the object of desire to all things, so far it appears to be in a certain respect indigent of the things to which it is related. It has therefore, if it be lawful so to speak, an ultimate vestige of indigence, just as on the contrary matter has an ultimate echo of the unindigent, or a most obscure and debile impression of the one. And language indeed appears to be here subverted. For so far as it is the one, it is also unindigent, since the principle has appeared to subsist according to the most unindigent and the one. At the same time, however, so far as it is the one, it is also the principle; and so far as it is the one it is unindigent, but so far as the principle, indigent. Hence so far as it is unindigent, it is also indigent, though not according to the same; but with respect to being that which it is, it is undigent; but as producing and comprehending other things in itself, it is indigent. This, however, is the peculiarity of the one; so that it is both unindigent and indigent according to the one. Not indeed than it is each of these, in such a manner as we divide it in speaking of it, but it is one alone; and according to this is both other things, and that which is indigent. For how is it possible, it should not be indigent also so far as it is the one? Just as it is all other things which proceed from it. For the indigent also is, something belonging to all things. Something else, therefore, must be investigated which in no respect has any kind of indigence. But of a thing of this kind it cannot with truth be asserted that it is the principle, nor can it even be said of it that it is most unindigent, though this appears to be the most venerable of all assertions.[4]

Introduction to the Philosophy and Writings of Plato — Part 7