He turned to the wizards as they hurried up.
‘Stand well back,’ he commanded. ‘And be prepared to run.’
He pointed the octiron staff at the half-sunken thing. A bolt of octarine light shot from its tip and struck the egg, exploding into a shower of sparks that left blue and purple after-images.
There was a pause. A dozen wizards watched the egg expectantly.
A breeze shook the willow trees in a totally unmysterious way.
Nothing else happened.
‘Er-’ Spelter began.
And then came the first tremor. A few leaves fell out of the trees and some distant water bird took off in fright.
The sound started as a low groaning, experienced rather than heard, as though everyone’s feet had suddenly become their ears. The trees trembled, and so did one or two wizards.
The mud around the egg began to bubble.
And exploded.
The ground peeled back like lemon rind. Gouts of steaming mud spattered the wizards as they dived for the cover of the trees. Only Coin, Spelter and Carding were left to watch the sparkling white building arise from the meadow, grass and dirt pouring off it. Other towers erupted from the ground behind them; buttresses grew through the air, linking tower with tower.
Spelter whimpered when the soil flowed away from around his feet, and was replaced by flagstones flecked with silver. He lurched as the floor rose inexorably, carrying the three high above the treetops.
The rooftops of the University went past and fell away below them. Ankh-Morpork spread out like a map, the river a trapped snake, the plains a misty blur. Spelter’s ears popped, but the climb went on, into the clouds.
They emerged drenched and cold into blistering sunlight with the cloud cover spreading away in every direction. Other towers were rising around them, glinting painfully in the sharpness of the day.
Carding knelt down awkwardly and felt the floor gingerly. He signalled to Spelter to do the same.
Spelter touched a surface that was smoother than stone. It felt like ice would feel if ice was slightly warm, and looked like ivory. While it wasn’t exactly transparent, it gave the impression that it would like to be.
He got the distinct feeling that, if he closed his eyes, he wouldn’t be able to feel it at all.
He met Carding’s gaze.
‘Don’t look at, um, me,’ he said. ‘I don’t know what it is either.’
They looked up at Coin, who said: ‘It’s magic.’
‘Yes, lord, but what is it made of?’ said Carding.
‘It is made of magic. Raw magic. Solidified. Curdled. Renewed from second to second. Could you imagine a better substance to build the new home of sourcery?’
The staff flared for a moment, melting the clouds. The Discworld appeared below them, and from up here you could see that it was indeed a disc, pinned to the sky by the central mountain of Cori Celesti, where the gods lived. There was the Circle Sea, so close that it might even be possible to dive into it from here; there was the vast continent of Klatch, squashed by perspective. The Rimfall around the edge of the world was a sparkling curve.
‘It’s too big,’ said Spelter under his breath. The world he had lived in hadn’t stretched much further than the gates of the University, and he’d preferred it that way. A man could be comfortable in a world that size. He certainly couldn’t be comfortable about being half a mile in the air standing on something that wasn’t, in some fundamental way, there.
The thought shocked him. He was a wizard, and he was worrying about magic.
He sidled cautiously back towards Carding, who said: ‘It isn’t exactly what I expected.’
‘Um?’
‘It looks a lot smaller up here, doesn’t it.’
‘Well, I don’t know. Listen, I must tell you-’