Wherefore let us consider more carefully that example which we have adduced, wherein it was shown that not knowing a thing is different from not thinking [conceiving] of it; and that it may so happen that a man knows something of which he is not thinking, when he is thinking of something else, not of that. When any one, then, who is skilled in two or more branches of knowledge is thinking of one of them, though he is not thinking of the other or others, yet he knows them. But can we rightly say, This musician certainly knows music, but he does not now understand it, because he is not thinking of it; but he does now understand geometry, for of that he is now thinking? Such an assertion, as far as appears, is absurd. What, again, if we were to say, This musician certainly knows music, but he does not now love it, while he is not now thinking of it; but he does now love geometry, because of that he is now thinking, -- is not this similarly absurd? But we say quite correctly, This person whom you perceive disputing about geometry is also a perfect musician, for he both remembers music, and understands, and loves it; but although he both knows and loves it, he is not now thinking of it, since he is thinking of geometry, of which he is disputing. And hence we are warned that we have a kind of knowledge of certain things stored up in the recesses of the mind, and that this, when it is thought of, as it were, steps forth in public, and is placed as if openly in the sight of the mind; for then the mind itself finds that it both remembers, and understands, and loves itself, even although it was not thinking of itself, when it was thinking of something else. But in the case of that of which we have not thought for a long time, and cannot think of it unless reminded; that, if the phrase is allowable, in some wonderful way I know not how, we do not know that we know. In short, it is rightly said by him who reminds, to him whom he reminds, You know this, but you do not know that you know it; I will remind you, and you will find that you know what you had thought you did not know. Books, too, lead to the same results, viz. those that are written upon subjects which the reader under the guidance of reason finds to be true; not those subjects which he believes to be true on the faith of the narrator, as in the case of history; but those which he himself also finds to be true, either of himself, or in that truth itself which is the light of the mind. But he who cannot contemplate these things, even when reminded, is too deeply buried in the darkness of ignorance, through great blindness of heart and too wonderfully needs divine help, to be able to attain to true wisdom.
10. For this reason I have wished to adduce some kind of proof, be it what it might, respecting the act of conceiving, such as might serve to show in what way, out of the things contained in the memory, the mind's eye is informed in recollecting, and some such thing is begotten, when a man conceives, as was already in him when, before he conceived, he remembered; because it is easier to distinguish things that take place at successive times, and where the parent precedes the offspring by an interval of time. For if we refer ourselves to the inner memory of the mind by which it remembers itself, and to the inner understanding by which it understands itself, and to the inner will by which it loves itself, where these three always are together, and always have been together since they began to be at all, whether they were being thought of or not; the image of this trinity will indeed appear to pertain even to the memory alone; but because in this case a word cannot be without a thought (for we think all that we say, even if it be said by that inner word which belongs to no separate language), this image is rather to be discerned in these three things, viz. memory, intelligence, will. And I mean now by intelligence that by which we understand in thought, that is, when our thought is formed by the finding of those things, which had been at hand to the memory but were not being thought of; and I mean that will, or love, or preference which combines this offspring and parent, and is in some way common to both. Hence it was that I tried also, viz. in the eleventh book, to lead on the slowness of readers by means of outward sensible things which are seen by the eyes of the flesh; and that I then proceeded to enter with them upon that power of the inner man whereby he reasons of things temporal, deferring the consideration of that which dominates as the higher power, by which he contemplates things eternal. And I discussed this in two books, distinguishing the two in the twelfth, the one of them being higher and the other lower, and that the lower ought to be subject to the higher; and in the thirteenth I discussed, with what truth and brevity I could, the office of the lower, in which the wholesome knowledge of things human is contained, in order that we may so act in this temporal life as to attain that which is eternal; since, indeed, I have cursorily included in a single book a subject so manifold and copious, and one so well known by the many and great arguments of many and great men, while manifesting that a trinity exists also in it, but not yet one that can be called an image of God.