In his teaching as to how this vision is achieved, Saint Thomas proves the richness of his intelligence. The glory of Heaven, the essence of its joy for me, will be to know God even as I am known. The intimate acquaintance God has of my whole nature, His deep comprehension of my passing thoughts, His perfect and subtle understanding of my strength, will be somehow paralleled by my own true knowledge of Him. But how is this to be done? How am I, a creature, to get into my limited reason a perfect idea of the Infinite? Whatever I do know comes to me by means of an idea; that is, I obtain my knowledge of things not by directly taking them into my mind, but by seizing in them the essential constituent of their being and formulating it in a sort of mental word of definition. The result is a kind of mental picture which contains the barest elements of what I am understanding. Hence the perfection of my knowledge of anything depends entirely upon the adequacy of my idea of it. If that mental picture corresponds to the thing itself really, then my knowledge is all right; but if there is no such correspondence, then obviously I have not grasped the meaning of what has been presented to my mind. Now it is evident that by no manner of means can any idea represent God adequately. He cannot be cramped into any human idea. Hence it would seem that I could never see God as He is.
Then at once Saint Thomas points out the way the difficulty is overcome. It is really simple, but overpowering. No idea can perfectly represent God. Then God must Himself take the place of the idea. No longer shall my ideas in Heaven be as here on earth the mere fabrication of my own intelligence, but, in the case of the Vision of God, it is He Himself who enters familiarly into my intelligence and so impresses Himself upon its surface that He becomes part of its very mechanism. So intimate is He with its texture that it is He who is its light and its informant. In other words, and to repeat, my idea of God in Heaven is not as my idea of God on earth. Here I have seized it for myself, and have fashioned from what I have been told, and what I have read, an idea of what He is in Himself. I have gathered together notions of a self-existing Being, who is just, wise, truthful, powerful, loving, merciful, etc. I have got more or less vaguely impressions (even though I cannot properly express them) as to what wisdom, justice, mercy, etc., mean. These I lump together and form for myself, under the light of Faith and Reason, an idea of God. But in Heaven there will be no such process. God is at once in Himself our idea. Hence the souls in bliss see Him adequately, fully, wholly, for they see Him by means of Himself without symbol, sign, representation, but with His single and immediate Presence. Not as in grace are we made partakers of the Divine Nature, but He is almost a partaker of ours.
I shall in Heaven see my Maker, yet not lose my own individual being. I shall be absorbed in Him, see Him steadily face to face. All the veils that at present hide Him from me shall be rent asunder, every separating influence, every reflecting mirror or darkened glass (lest His glory dazzle my weak sight), shall be ruthlessly cast aside, and in the absolute contemplation of Himself shall my happiness find its complete satisfaction. He shall be one with me; yet without His strong, overwhelming Being making me cease to be myself. He shall live in me; yet shall I myself live. It is all a very great wonder - this perfect knowledge, complete, adequate, obtained by no act of mine, but by the infusion into my soul of Himself. As Saint Augustine noted it: "Not we shall enter into all joy, but all joy shall enter into us." Nor can this end in mere wonder, for there is to follow, consequent upon such a vision, the utmost rapture of love. The heart will itself break out into perfect songs of love. But it is the vision itself by which the soul attains perfection. The apprehension is an act of intelligence, a seeing, beholding of God. Oh, how careful must I be of that frail, faltering reason which must one day be possessed by God! How clean must be that temple which God shall one day enter in! How guarded must it be from the profane defiling of evil thoughts, how ceaselessly defended from evil assaults! Here I must prepare for that ultimate embrace.
- text taken from by Father Bede Jarrett, O.P.