At the climactic moment of Vernor Vinge's sf novel A Fire Upon the Deep comes a memorable scene which attempts to tiptoe along the edge of reality --- and which perhaps is dependent enough on previous context to need no spoiler warning for those who have yet to read the book:
For Pham Nuwen there was no pain. The last minutes of his life were beyond any description that might be rendered in the Slowness or even in the Beyond.
So try metaphor and simile. It was like . . . it was like . . . Pham stood with Old One an a vast and empty beach. Ravna and Tines were tiny creatures at their feet. Planets and stars were the grains of sand. And the sea had drawn briefly back, letting the brightness of thought reach here where before had been darkness. The Transcendence would be brief. At the horizon, the drawn-back sea was building, a dark wall higher than any mountain, rushing back upon them. He looked up at the enormity of it. Pham and godshatter and Countermeasure would not survive that submergence, not even separately. They had triggered catastrophe beyond mind, a vast section of the Galaxy plunged into Slowness, as deep as Old Earth itself, and as permanent.