He felt much calmer, somehow, now that he was in Dumbledore’s office, knowing he would shortly be telling him about the dream. Harry looked up at the walls behind the desk. The patched and ragged Sorting Hat was standing on a shelf. A glass case next to it held a magnificent silver sword with large rubies set into the hilt, which Harry recognized as the one he himself had pulled out of the Sorting Hat in his second year. The sword had once belonged to Godric Gryffindor, founder of Harry’s House. He was gazing at it, remembering how it had come to his aid when he had thought all hope was lost, when he noticed a patch of silvery light, dancing and shimmering on the glass case. He looked around for the source of the light and saw a sliver of silver-white shining brightly from within a black cabinet behind him, whose door had not been closed properly. Harry hesitated, glanced at Fawkes, then got up, walked across the office, and pulled open the cabinet door.

A shallow stone basin lay there, with odd carvings around the edge: runes and symbols that Harry did not recognize. The silvery light was coming from the basin’s contents, which were like nothing Harry had ever seen before. He could not tell whether the substance was liquid or gas. It was a bright, whitish silver, and it was moving ceaselessly; the surface of it became ruffled like water beneath wind, and then, like clouds, separated and swirled smoothly. It looked like light made liquid—or like wind made solid—Harry couldn’t make up his mind.

He wanted to touch it, to find out what it felt like, but nearly four years’ experience of the magical world told him that sticking his hand into a bowl full of some unknown substance was a very stupid thing to do. He therefore pulled his wand out of the inside of his robes, cast a nervous look around the office, looked back at the contents of the basin, and prodded them.

The surface of the silvery stuff inside the basin began to swirl very fast.

Harry bent closer, his head right inside the cabinet. The silvery substance had become transparent; it looked like glass. He looked down into it, expecting to see the stone bottom of the basin—and saw instead an enormous room below the surface of the mysterious substance, a room into which he seemed to be looking through a circular window in the ceiling.