And then Vimes' train of thought came to a screeching halt. A cow had been struck, people had been injured, and, as was the way of these things, a single, flaming wheel was now careening across the countryside, where it would eventually embed itself in a farmhouse, and leave many people wondering where on earth it had come from.

"...Er," he managed, "I was being metaphorical, actually. In this instance the watch'd be you, and the spring is, er." Where had he been going with that, anyway? "The point is, Minimus, that if you keep going without a break you'll snap."