Walter sends Roland a vision of the universe's birth

The universe was void. Nothing moved. Nothing was.
The gunslinger drifted, bemused.
“Let’s have a little light,” the voice of the man in black said nonchalantly, and there was light. The gunslinger thought in a detached way that light was pretty good.
“Now darkness overhead with stars in it. Water down below.”
It happened. He drifted over endless seas. Above, the stars twinkled endlessly, yet he saw none of the constellations which had guided him across his long life.
“Land,” the man in black invited, and there was; it heaved itself out of the water in endless, galvanic convulsions. It was red, arid, cracked and glazed with sterility. Volcanoes blurted endless magma like giant pimples on some ugly adolescent’s baseball head.
“Okay,” the man in black was saying. “That’s a start. Let’s have some plants. Trees. Grass and fields.”
There was. Dinosaurs rambled here and there, growling and whoofing and eating each other and getting stuck in bubbling, odiferous tarpits. Huge tropical rain-forests sprawled everywhere. Giant ferns waved at the sky with serrated leaves. Beetles with two heads crawled on some of them. All this the gunslinger saw. And yet he felt big.
“Now bring man,” the man in black said softly, but the gunslinger was falling . . . falling up. The horizon of this vast and fecund earth began to curve. Yes, they had all said it curved, his teacher Vannay had claimed it had been proved long before the world had moved on. But this—
Further and further, higher and higher. Continents took shape before his amazed eyes, and were obscured with clocksprings of clouds. The world’s atmosphere held it in a placental sac. And the sun, rising beyond the earth’s shoulder—
He cried out and threw an arm before his eyes.
“Let there be light!”
The voice no longer belonged to the man in black. It was gigantic, echoing. It filled space, and the spaces between space.
“Light!”
Falling, falling.
The sun shrank. A red planet stamped with canals whirled past him, two moons circling it furiously. Beyond this was a whirling belt of stones and a gigantic planet that seethed with gases, too huge to support itself, oblate in consequence. Further out was a ringed world that glittered like a precious gem within its engirdlement of icy spicules.
“Light! Let there be—”
Other worlds, one, two, three. Far beyond the last, one lonely ball of ice and rock twirled in dead darkness about a sun that glittered no brighter than a tarnished penny.
Beyond this, darkness.
“No,” the gunslinger said, and his word on it was flat and echoless in the black. It was darker than dark, blacker than black. Beside this, the darkest night of a man’s soul was as noonday, the darkness under the mountains a mere smudge on the face of Light. “No more. Please, no more now. No more—”
“LIGHT!”
“No more. No more, please—”
The stars themselves began to shrink. Whole nebulae drew together and became glowing smudges. The whole universe seemed to be drawing around him.
“Please no more no more no more—”
The voice of the man in black whispered silkily in his ear: “Then renege. Cast away all thoughts of the Tower. Go your way, gunslinger, and begin the long job of saving your soul.”
He gathered himself. Shaken and alone, enwrapt in the darkness, terrified of an ultimate meaning rushing at him, he gathered himself and uttered the final answer on that subject:
“NEVER!”
“THEN LET THERE BE LIGHT!”
And there was light, crashing in on him like a hammer, a great and primordial light. Consciousness had no chance of survival in that great glare, but before it perished, the gunslinger saw something clearly, something he believed to be of cosmic importance. He clutched it with agonized effort and then went deep, seeking refuge in himself before that light should blind his eyes and blast his sanity.
He fled the light and the knowledge the light implied, and so came back to himself. Even so do the rest of us; even so the best of us.
IV
It was still night—whether the same or another, he had no immediate way of knowing. He pushed himself up from where his demon spring at the man in black had carried him and looked at the ironwood where Walter o’ Dim (as some along Roland’s way had named him) had been sitting. He was gone.
A great sense of despair flooded him—God, all that to do over again—and then the man in black said from behind him: “Over here, gunslinger. I don’t like you so close. You talk in your sleep.” He tittered.
The gunslinger got groggily to his knees and turned around. The fire had burned down to red embers and gray ashes, leaving the familiar decayed pattern of exhausted fuel. The man in black was seated next to it, smacking his lips with unlovely enthusiasm over the greasy remains of the rabbit.
“You did fairly well,” the man in black said. “I never could have sent that vision to your father. He would have come back drooling.”
“What was it?” the gunslinger asked. His words were blurred and shaky. He felt that if he tried to rise, his legs would buckle.
“The universe,” the man in black said carelessly. He burped and threw the bones into the fire where they first glistened and then blackened. The wind above the cup of the golgotha keened and moaned.
-The Gunslinger