Thief of Time - Genua

'Ooo, miss, miss, ooo ...' A boy called Gordon cautiously admitted that it might be three o'clock, to the audible disappointment of the inflatable Vincent.

'That's right,' said Miss Susan. 'Can anyone tell me why it's three o'clock in Genua while it's twelve o'clock in Ankh-Morpork?'

There was no avoiding it this time. If Vincent's hand had gone up any faster it would have fried by air friction. 'Yes, Vincent?'

'Ooo miss speed of light miss it goes at six hundred miles an hour and at the moment the sun's rising on the Rim near Genua so twelve o'clock takes three hours to get to us miss!'

Miss Susan sighed.

'Very good, Vincent,' she said, and stood up. Every eye in the room watched her as she crossed over to the Stationery Cupboard. It seemed to have travelled with them and now, if there had been anyone to note such things, they might have seen faint lines in the air that denoted walls and windows and doors. And if they were intelligent observers, they'd have said: so ... this classroom is in some way still in Ankh-Morpork and also in Genua, is it? Is this a trick? Is this real? Is it imagination? or is it that, to this particular teacher, there is not much of a difference?

The inside of the cupboard was also present, and it was in that shadowy, paper-smelling recess that she kept the stars.

***

Thief of Time - p28-29