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The light and shade in the mysteries of God's life
As we have seen, the attributes of God relative to His being are simplicity, infinity, immensity, and eternity. Before passing on to treat of those which, like wisdom and providence, relate to His operations, it will be well to say something of the divine incomprehensibility, which is so marked a feature of the divine governance in certain of its ways.
Therein will be found an important lesson for our own spiritual life. The point we shall particularly stress is that, although from certain angles God is presented to us in the clearest light, in other respects He remains in the deepest shadow. As in paintings we have light and shade, so also in the teachings of revelation we find lights and shadows, which are incomparably more beautiful than those we admire in the great masters. And the same lights and shadows in which God is represented to us will be found reproduced to some extent in our own spiritual life; for grace is a participation in the Divine nature, or in the intimate life of God.
The high lights in the Divinity
Let us speak first of God's features that are quite clear to us. By the natural exercise of our reason, apart even from faith, we are able here on earth to demonstrate the existence of God, the first mover of spiritual and corporeal beings, the first cause of everything that exists, the necessary being, the sovereign good, and the source of order in the world.
In the mirror of created things we discover a reflection of God's absolute perfections and thus acquire a positive knowledge of whatever is similar or analogically common in God and His works: His reality, His actuality, His goodness, wisdom, and power.
When we wish to point out His distinctive characteristics, we do so by way of negation or by relating Him to the object of our experience. Thus we speak of God as the infinite or non-finite Being, as unchangeable, or again as the supreme good.
These rational convictions, already of themselves firmly established, receive further confirmation from Divine revelation accepted through faith. These convictions are adamantine and unassailable. To us it is quite clear that God cannot: exist without being infinitely perfect, that He can neither be deceived Himself nor deceive us, that He cannot will what is evil or be in any way the cause of sin. Indeed we are incomparably more certain of the rectitude of God's intentions than we are of even the best of our own. From this angle God stands out before our minds in a light almost dazzlingly clear. Again, it is quite evident to us that on the one hand God is the author of all good, including also the good contained in our meritorious consent, and that on the other hand He never demands the impossible. Nothing can prevail against these supremely evident truths, which have the force of conviction for every right mind that is open to truth. Obviously God cannot exist without being at once supremely just and supremely merciful, supremely wise and at the same time supremely free. And yet, with all this dazzling clarity, there is in God that which for us is very obscure. What is the cause of this?
The light-transcending darkness in God
The obscurity confronting us in God is owing to the fact that He is far too luminous for the feeble sight of our intellect, which is unable to endure His infinite splendor.
To us God is invisible and incomprehensible for the reason that, as Scripture says, "He inhabiteth light inaccessible" (1 Tim. 6:16), which has for. us the same effect as darkness. To the owl, in the order of sense perception, darkness appears to begin at sunrise, because its feeble sight can perceive only the faint glimmer that comes with the twilight or just before the dawn, and is dazzled by the excessive brilliance of the sun. Where God, the Sun of the spirit world, is concerned, our intellect is in much the same condition. Its intellectuality is of the lowest degree) being inferior to that of the angel; it sees intelligible truths only dimly and in a half-light, as it were, as reflected in a mirror of a lower order, the things of sense. 
As St. Thomas notes (Ia, q. 76, a. 5), our intellect requires to be united with the senses so as to be presented with its proper object. This lowest degree of intellectuality attains first of all in cognition its proper object, the being of sensible things, which is the lowest degree of the intelligible; and in that object it acquires a very imperfect knowledge of God's existence, and sees the reflection of His Divine perfections.
Whereas, then, many things are invisible through not being sufficiently luminous or not sufficiently illuminating, God is invisible because for us He is far too luminous. 
That God, Who is pure spirit, cannot be seen by bodily eyes, is quite evident, since these perceive only what is sensible. But neither can He be seen by a created intellect when this is left to its purely natural resources. Not even the highest among the Angels can directly see God through the purely natural power of their intellect; for them, too, God is a light overpowering in its intensity, a naturally inaccessible light. For the Angels, the sole natural means of knowing God is in the mirror of spiritual creatures which are their proper object, this mirror being their own essence or that of other Angels. They have a natural knowledge of God as the author of their nature, but they cannot have a natural knowledge of Him in His intimate life or see Him face to face.
To see God, the Angels, like human souls, must have received the light of glory, that supernatural light to which their nature has no claim whatever, but which is infused in order to fortify their intellects and enable them to endure the brightness of Him who is light itself.  God Himself cannot give us a created idea capable of representing His divine essence as it is in itself. Such an idea must always be imperfect, intelligible only by participation, and hence wholly inadequate to represent, as it really is, that eternally subsistent, purely intellectual flash, the essence of God with its infinite truth.
If God wishes to reveal Himself as He really is, this can be only by direct vision with no created idea intervening, unfolding to our gaze the Divine essence in all its splendor, and at the same time sustaining and fortifying our intellect, which when left to itself is too feeble to behold it. 
It is in this way the blessed in Heaven see God. We, too, desire to attain to this same vision, in which our everlasting happiness will consist. 
God is therefore invisible to our mental as well as to our bodily sight because of the exceeding intensity of His radiance.
But how is it that in this invisible God there is so much that is transparently clear to us and at the same time so much, that is profoundly obscure? What is the source of this fascinating, mysterious light and shade?
Evidently God cannot exist without being supremely wise, supremely good, and supremely just; He is the author of all good and never commands what is impossible. Then how is it that side by side with this dazzling radiance there is so much obscurity?
It is due to the fact that our knowledge of the Divine perfections is obtained solely from their reflection in creatures. Although we can enumerate them one after another, we are unable naturally to perceive how they are united in the intimate life of God, in the eminence of the Deity. This intimate mode of their union is entirely hidden from us; its radiance is too overpowering, it is too exalted to be reflected in any created mirror. As we said above, where the Deity is concerned, we are like men who have never seen white light but only the seven colors of the rainbow in the clear waters of a lake.
Doubtless in the Divine rainbow we see its various colors: that God, for example, is infinitely wise and supremely free. But we cannot see how infinite wisdom is intimately reconciled with a good pleasure so free as to appear to us at certain times sheer caprice. And yet, however surprising it may seem, this good pleasure is still supremely wise. We accept it in the obscurity of faith, but only in Heaven will it be clearly seen.
Again, we are certain that God is infinitely merciful, that He is also infinitely just, and that He exercises both His mercy and His justice with a sovereign freedom in which wisdom is never wanting. If, says St. Augustine, to the good thief was granted the grace of a happy death, it was through mercy; if it was denied to the other, it was through justice. Here we have a mystery: we cannot see how infinite mercy, infinite justice, and a sovereign liberty are intimately reconciled. For this we must have a direct intuition of the Divine essence, of the Deity, in the eminence of which these perfections are reconciled, and that far more profoundly, more perfectly, than the seven colors are contained in white light.
In God truths that relate to each attribute considered apart are quite clear. But so soon as we consider their intimate reconciliation, there descends a darkness that transcends the
Once again, we see quite distinctly that in His exceeding goodness and power God cannot permit evil unless for some greater good, as He permits persecution for the glory of the Martyrs. But for us this greater good is often very obscure, to be seen clearly only in Heaven. This truth is eloquently, brought out in the Book of Job.  There is enough light for our Lord to have said: "He that followeth me walketh not in darkness."  Thus, however obscure in itself our cross may be, we are able to bear it, all being made clear to us when we reflect that it is ordained for the good of our souls and the glory of God.
Our life is frequently cast in this mysterious light and shade, which appears in our very existence when this is viewed in its relations with Him who, without fully revealing Himself as yet, is ever drawing us to Him.
Hence arises that ardent desire to see God, that supernatural, efficacious desire proceeding from infused hope and charity. Hence, too, in every man arises a natural and inefficacious desire, a natural velleity, to behold God face to face, if only to solve the enigma how attributes so apparently opposed as infinite justice and infinite mercy are reconciled in Him. 
From this it follows that what is obscure and incomprehensible for us in God transcends what is clearly seen. Here, in fact, the darkness is light-transcending. What the mystics call the great darkness is the Deity, the intimate life of God, the "light inaccessible" mentioned by St. Paul (1 Tim. 6: 6).
We now understand what St. Teresa means when she says: "The more obscure the mysteries of God, the greater is my devotion to them." She indeed realized that this obscurity is not that of absurdity or incoherence, but the obscurity of a light that is too intense for our feeble vision.
In this Divine light and shade, then, the shadows transcend the light. Faith tells us that this impenetrable obscurity is the sovereign good in its more intimate characteristics, so that it is to this absolutely eminent Goodness, though still a mystery incomprehensible to the intellect, that our charity cleaves; the food of love in this life is mystery, which it adores. Here on earth love is superior to the intellect. As St. Thomas says, so long as we have not attained to the beatific vision of the Divine essence, our intellect, with its very imperfect conception of God, brings Him down in some sort to our level, imposing upon Him as it were the limitations of our own restricted ideas; whereas love does not bring God down to our level, but uplifts us and unites us to Him (Ia, q. 82, a. 3; IIa IIae, q. 23, a. 5; q. 27, a. 4).
Therefore in this Divine light and shade the shadows transcend the light and, for the Saints here on earth, this light-transcending darkness exerts such an attraction on the love uniting them to God. "The just man lives by faith" (Rom. 1:17) and finds his support not only in its light but also in the Divine darkness which corresponds to all that is most intimate in God. It is upon the incomprehensibility of the Divine life that the contemplative is reared; he grasps the full meaning of that phrase of St. Thomas: "Faith is of things unseen" (IIa IIae, q. 1, a. 4, 5).
Finally, even for the blessed in Heaven God remains in a certain sense incomprehensible, although they see Him face to face. No creature, no idea intervenes between Him and them in their vision of Him, and yet that vision can never be comprehensive like the vision God alone naturally has of Himself. Why is this?
St. Thomas provides a simple explanation: To comprehend a thing in the true sense of the word, is to know it as far as it can be known. A person can know a proposition of geometry without comprehending it, as is the case with anyone who accepts it on the word of the learned; he knows all the elements in the proposition (subject, verb, predicate) but he does not grasp the proof, and hence does not know it as far as it can be known (cf. Ia, q. 12, a. 7). Thus the pupil who knows his master's teaching in all its parts does not penetrate so deeply as his master, for he has only a confused grasp of the radical connection of each part with the fundamental principles. Or again, a shortsighted person will see the whole of a landscape, but not so distinctly as one 'whose eyesight is good.
So also in Heaven each one of the blessed sees the whole of the Divine essence, for it is indivisible. But, since it is the infinite truth, infinitely knowable, they cannot penetrate it so deeply as God. The degree of penetration is according to the intensity of the light of glory they have received, and this again is in proportion to their merits and their love for God acquired here on earth. Consequently they cannot take in at a glance, as God does, the countless possible beings His Divine essence virtually contains, and which He could create if He chose.
The divine light and shade of which we have just been speaking contain much that will enlighten our own spiritual life. Our Lord thus expresses it: "He that followeth me walketh not in darkness, but shall have the light of life" (John 8:12).
Since the life of grace within us is a participation in the intimate life of God, it, too, will be for us a mysterious. light and shade, which we must be careful not to distort or confuse. Grace brings us enlightenment, consolation, and peace, that tranquillity which comes from order. These are the high lights; we are no longer in the "shadow of death." On the other hand, it is on a plane so exalted that it is beyond the reach of reason; we can never have absolute certitude that we are in the state of grace, though we may have sufficient indications of its presence to permit our approaching the holy table.
Moreover, along the path we have to pursue through life are lights and shadows of another sort. The precepts of God and His Church, the orders of superiors, the advice of spiritual directors --- these are rays of light. But we find shadows, too, lurking in the depths of conscience. Not always can we easily distinguish true humility from false, dignity from pride, confidence from presumption, fortitude from temerity. Lastly --- and it is here especially that the interior drama lies --- in this obscurity characteristic of our life there is the darkness descending from above, the obscurity of grace with its over-powering radiance, and that other darkness from below, arising from the lower elements in our disordered nature.
Let us often ask the good God to enlighten us through the gifts of the Holy Spirit, that we may walk aright amid this interior light and shadow. To deny the light because of the shadows and thus substitute the absurd for the mystery, would result in error and discouragement. Let us leave the mystery its rightful place. Let us ask of God the grace to distinguish between the light-transcending darkness from above and that lower darkness which is the darkness of death. And, that we may the more surely obtain this grace, let us often repeat this prayer: "Grant me, O Lord, to know the obstacles that I am more or less conscious of placing in the way of grace and its working in me, and give me the strength to remove them, no matter what it may cost me." In this way we shall discover the true light, and if darkness persists it will be the darkness from on high, that which enables the just man to live; for to our poor intellect it is but an aspect of the light of life and of the sovereign good. This is what is meant by these words: "He that followeth me walketh not in darkness, but shall have the light of life."  He who follows me walks neither in the darkness of religious ignorance nor in the darkness of sin and condemnation, but in the light, for "I am the way, the truth, and the life"; therefore "he shall have the light of life," which shall never be extinguished.
1. This is the element of truth in Plato's allegory of the cave.
2. Scripture more often speaks of that lower darkness in which the soul perishes; but it also speaks of the higher obscurity of faith, corresponding to the "light inaccessible" where God abides. Of the lower darkness it is said: The wicked man "shall not depart out of darkness" (Job 15:30). The nations before the coming of Christ "sat in darkness and in the shadow of death" (Ps. 106:10). It was in the midst of this darkness that the Light of salvation descended from on high: "To the righteous a light is risen up in darkness" (Ps. 111:4); "The people that walked in darkness have seen a great light" (Is. 9:2; Matt. 4:16); "For you were heretofore darkness, but now light in the Lord" (Eph. 5:8); "God is light, and in Him there is no darkness" (1 John 1:5).
But sometimes, relatively to us, God is spoken of as a Divine darkness: "Clouds and darkness are round about Him. ... His lightnings have shone forth in the world" (Ps. 96:2, 4); "And the glory of the Lord dwelt upon Sinai, covering it with a cloud six days: and the seventh day He called him out of the midst of the cloud" (Ex. 24:16; cf. Ex. 19:9; 20:21).
3. Cf. St. Thomas, Ia, q. 12, a. 4; q. 56, a. 3.
4. Cf. St. Thomas, Ia, q. 12, a. 2.
5. Cf. St. Thomas, Ia, q. 12, a. 1.
6. Cf. Comment. S. Thomae in Job, chaps. 4, 6, 8.
7. John 8:12.
8. Cf. St. Thomas, Ia, q. 12, a. 1.
9. Cf. John 8:12.