Slowly, carefully, she crept forwards into that immense emptiness. The floor glittered—snaking lines of bright metal, set into the black rock. The ceiling, if there was one, was shrouded in darkness. A high balcony ran around the walls a good twenty strides up, another far above that, then another, and another, vague in the half-light. Above all, a beautiful device hung. Rings of dark metal, great and small, gleaming discs and shining circles, marked with strange writings. All moving. All revolving, one ring about the other, and at their centre a black ball, the one point of perfect stillness.

She turned round, and round, or perhaps she stood still and the room turned about her. She felt dizzy, drunken, breathless. The bare rock soared away into the black, rough stones without mortar, no two alike. Ferro tried to imagine how many stones the tower was made of.

Thousands. Millions.

What had Bayaz said, on the island at the edge of the World? Where does the wise man hide a stone? Among a thousand. Among a million. The rings high above shifted gently. They pulled at her, and the black ball in the centre pulled at her most of all. Like a beckoning hand. Like a voice calling out her name.

She dug her fingers into the dry spaces between the stones and began to climb, hand over hand, up and up. It was easily done. As though the wall was meant to be climbed. Soon she swung her legs over the metal rail of the first balcony. On again, without pausing for breath, up and up. She reached the second balcony, sticky with sweat in the dead air. She reached the third, breath rasping. She gripped the rail of the fourth, and pulled herself over. She stood, staring down.

Far below, at the bottom of a black abyss, the whole Circle of the World lay on the round floor of the hall. A map, the coastlines picked out in shining metal. Level with Ferro, filling almost all the space within the gently curving gallery, suspended on wires no thicker than threads, the great mechanism slowly revolved.

She frowned at the black ball in its centre, her palms tingling. It seemed to hover there, without support. She should have wondered how that could be, but all she could think about was how much she wanted to touch it. Needed to. She had no choice. One of the metal circles drifted close to her, gleaming dully.

Sometimes it is best to seize the moment.