Ponder shook his head.

"Thank you, Archchancellor, but I'm far too busy for you to help me," he said.

"But will it work?"

"It has to, sir. It's a million-to-one chance."

"Oh, then we don't have to worry. Everyone knows million-to-one chances always work."

"Yes, sir. So all I have to do is work out if there's still enough air outside the ship for Leonard to steer it, or how many dragons he will need to fire for how long, and if there will be enough power left to get them off again. I think he's travelling at nearly the right speed, but I'm not sure how much flame the dragons will have left, and I don't know what kind of surface he'll land on or anything they'll find there. I can adapt a few spells, but they were never devised for this sort of thing."

"Good man," said Ridcully.

"Is there anything we can do to help?" said the Dean.

Ponder gave the other wizards a desperate look. How would Lord Vetinari have handled this?

"Why, yes," he said brightly. "Perhaps you would be kind enough to find a cabin somewhere and come up with a list of all the various ways I could solve this? And I will just sit here and toy with a few ideas?"

"That's what I like to see," said the Dean. "A lad with enough sense to make use of the wisdom of his elders."

Lord Vetinari gave Ponder a faint smile as they left the cabin.

In the sudden silence Ponder . . . pondered. He stared at the orrery, walked around it, enlarged sections of it, peered at them, pored over the notes he had made about the power of dragon flight, stared at a model of the Kite, and spent a lot of time looking at the ceiling.

This wasn't the normal way of working for a wizard. A wizard evolved the wish, and then devised the command. He didn't bother much with observing the universe; rocks and trees and clouds could not have anything very intelligent to impart. They didn't even have writing on them, after all.

Ponder looked at the numbers he had scribbled. As a calculation, it was like balancing a feather on a soap bubble which wasn't there.

So he guessed.