It was a rectangular slab, three times his height but narrow enough to span with his arms, and it was made of some completely transparent material; indeed, it was not easy to see except when the rising sun glinted on its edges. It was certainly rather attractive, and though he was wisely cautious of most new things, he did not hesitate for long before sidling up to it. As nothing happened, he put out his hand, and felt a cold, hard surface. As the shadows lengthened, and the light drained from the sky, the crystal began to glow. Tantalising, ill-defined phantoms moved across its surface and in its depths. They coalesced into bars of light and shadow, then formed intermeshing, spoked patterns that began slowly to rotate.