“Perhaps, says he, it is not sufficient to say that it is the measure of mundane natures, nor to enumerate the goods of which it is the cause, but to the utmost of our power we should endeavour to apprehend its peculiarity. May we not therefore say, since its essence is most excellent, perfective of soul, and present to all things, that it is an intellect not only abiding but also subsisting in motion? Abiding indeed according to its inward energy, and by which it is truly eternal, but being moved according to its externally proceeding energy, by which it becomes the boundary of all transition. For eternity possessing permanency, both according to its inward energy, and that which it exerts to things eternal, Time being assimilated to it, according to the former of these energies, becomes separated from it according to the latter, abiding and being moved. And as with respect to the essence of the soul, we say that it is intelligible and at the same time generated, partible, and at the same time impartible, and are no otherwise able to apprehend its middle nature than by employing after a manner opposites, what wonder is there if, perceiving the nature of Time to be partly immoveable, and partly subsisting in motion, we, or rather not we, but prior to us, the philosopher, through _the eternal_, should indicate its intellectual monad abiding in sameness, and through _the moveable_ its externally proceeding energy, which is participated by soul and the whole world? For we must not think that the expression _the eternal_ simply indicates that Time is the image of eternity; for if this were the case, what would have hindered Plato from directly saying that it is the _image_, and not the _eternal image_ of eternity? But he was willing to indicate this very thing, that time has an eternal nature, but not in such a manner as animal itself [the paradigm of the universe] is said to be eternal. For that is eternal both in essence and energy; but Time is partly eternal, and partly, by its external gift, moveable. Hence theurgists call it eternal; and Plato very properly denominates it not _only_ so. For one thing is _alone_ moveable, both essentially and according to the participants of it, being _alone_ the cause of motion, as soul, and hence it _alone_ moves itself and other things; but another thing is _alone_ immoveable, preserving itself without transition, and being the cause to other things of a perpetual subsistence after the same manner, and to moveable natures through soul. It is necessary therefore, that the medium between these two extremes should be that which, both according to its own nature, and the gifts which it imparts to others, is immoveable and at the same time moveable, essentially immoveable indeed, but moved in its participants. A thing however of this kind is Time.