When I think about God as pure act, or as proceeding and triune, sooner or later I realize that I’ve been imagining a bright point of light in black space, or a beam of light shining into another beam of light. Similar things happen when I think of the angelic hierarchy. I realize that I’ve been imagining a rather ladder made out of light, in black space, doing nothing.
All of these images are far more pleasant and instructive when they are experienced from within- in the same way that dreams can be terrifying or intensely interesting to the one having them, though they tell a rather dull story taken by themselves. No one, for example, has ever dreamed a story as interesting to retell as Crime and Punishment or Don Quixote, but many people have had dreams that have moved them as much as reading those books.
These interior images are necessary to us, and they teach not only by symbolizing divine things, but also at those moments when we realize that they are false- Pure act is not a point of light in the black, the Trinity is not two light beams flowing into each other- from which billions of angels are generated at every moment. There is not even a moment in the Trinity. Both experiences, i.e. the experience of God in the symbol, and the negation of God within the symbol are necessary to ave right thinking about God. Any Atheist or Blasphemer could deny that God is present in the imagining of a beam of light- this takes no great insight. The mystical experience is not constituted by the negation alone, but by a negation of God’s presence from something that has shown us God’s presence. Ultimately, we must negate even our way of knowing from our knowledge of God, but this would be a meaningless negation if we had not come to know God through our mode of knowing.