I saw eternity the other night
Like a great ring of pure and endless light.
He goes on a bit after that but the power is in those first two lines. They have what I believe is called "onset"- the power of unqualified statement. No hesitation, no beating round the bush, no reaching after effect. Wordsworth hits the same transcendent note in The Intimations of Immortality Ode when he speaks of the human soul entering the world,
Not in utter nakedness
Nor in entire forgetfulness
But trailing clouds of glory..
And again he can't sustain it.
The problem with trying to say more, to describe a transcendent reality in detail, is that all we have to compare it with are the things of this world- and so you're always describing the things-that-are-more in terms of the things-that-are-less. So writers about heaven- those who been there or claimed to have been there- in dreams, or as astral travellers, or through having died and come back to life (which- thanks to modern medicine- is a more frequent occurence now than it used to be )- are reduced to talking about wonderful landscapes and cities of gold and angelic personages- all of them much brighter and more colourful and beautiful than anything that exists down here- and it turns into Shelley- all sublime mountains and crystal fountains- and the superlatives become numbing and conventional and wearisome. Unbelievable. Visions of Heaven in art are almost always disappointing. One artist who gets it right is Bosch. He has just the one image to match his hells- and it shows the ring of light that Vaughan describes. Better the glimpse, the hint of glory, than an attempt to convey the whole. Our minds and our senses just won't stretch that far.
Hell is easier. We have the language to describe Hell. Hell is like the everyday world, only worse. Worse is easier to describe than better. We can imagine worse, it's reality with knobs on- darker and grottier and more desperate and depressing. But a world that transcends the best we know on earth taxes language as it taxes the imagination. For instance people who have been there say Heaven has colours that simply don't exist on earth. How do you picture those? We just don't have the mental equipment.
I remember dreams that seem to have taken me to a place of heightened light and colour and mental awareness. I suspect I go there regularly- but the waking process wipes my mind and all I'm left with is fragments. In the one I recall most vividly I'm going down a country road on a bicycle feeling happy and at home. That's all there is to it. You have to take my word for it that the experience was more real than real- and completely convincing. If a dream presents us with a world that seems in all ways more concentrated than the so-called "real" world I don't think it unreasonable to suppose that the dream is the reality and the "real" world the shadow.