On The Holy Trinity by St. Augustine
Chapter 3.--The Unity of the Three Takes Place in Thought, Viz Of Memory, of Ternal Vision,and of Will Combining Both.
6. The rational soul, however, lives in a degenerate fashion, when it lives according to a trinity of the outer man; that is, when it applies to those things which form the bodily sense from without, not a praiseworthy will, by which to refer them to some useful end, but a base desire, by which to cleave to them. Since even if the form of the body, which was corporeally perceived, be withdrawn, its likeness remains in the memory, to which the will may again direct its eye, so as to be formed thence from within, as the sense was formed from without by the presentation of the sensible body. And so that trinity is produced from memory, from internal vision, and from the will which unites both. And when these three things are combined into one, from that combination itself they are called conception. And in these three there is no longer any diversity of substance. For neither is the sensible body there, which is altogether distinct from the nature of the living being, nor is the bodily sense there informed so as to produce vision, nor does the will itself perform its office of applying the sense, that is to be informed, to the sensible body, and of retaining it in it when informed; but in place of that bodily species which was perceived from without, there comes the memory retaining that species which the soul has imbibed through the bodily sense; and in place of that vision which was outward when the sense was informed through the sensible body, there comes a similar vision within, while the eye of the mind is informed from that which the memory retains, and the corporeal things that are thought of are absent; and the will itself, as before it applied the sense yet to be informed to the corporeal thing presented from without, and united it thereto when informed, so now converts the vision of the recollecting mind to memory, in order that the mental sight may be informed by that which the memory has retained, and so there may be in the conception a like vision. And as it was the reason that distinguished the visible appearance by which the bodily sense was informed, from the similitude of it, which was wrought in the sense when informed in order to produce vision (otherwise they had been so united as to be thought altogether one and the same); so, although that phantasy also, which arises from the mind thinking of the appearance of a body that it has seen, consists of the similitude of the body which the memory retains, together with that which is thence formed in the eye of the mind that recollects; yet it so seems to be one and single, that it can only be discovered to be two by the judgment of reason, by which we understand that which remains in the memory, even when we think it from some other source, to be a different thing from that which is brought into being when we remember, that is, come back again to the memory, and there find the same appearance. And if this were not now there, we should say that we had so forgotten as to be altogether unable to recollect. And if the eye of him who recollects were not informed from that thing which was in the memory, the vision of the thinker could in no way take place; but the conjunction of both, that is, of that which the memory retains, and of that which is thence expressed so as to inform the eye of him who recollects, makes them appear as if they were one, because they are exceedingly like. But when the eye of the concipient is turned away thence, and has ceased to look at that which was perceived in the memory, then nothing of the form that was impressed thereon will remain in that eye, and it will be informed by that to which it had again been turned, so as to bring about another conception. Yet that remains which it has left in the memory, to which it may again be turned when we recollect it, and being turned thereto may be informed by it, and become one with that whence it is informed.