It’s amazing what a summer can do. Some of the boys who had started the school holidays in June thin­limbed and slight, with the high­ pitched voices of children, returned to the classrooms in August tall and gangly, with whopping great hands and feet and voices like rust. There was a lethargy about them now as well, something you don’t see in young children but which throws a shroud over many teenagers.

The girls had shot up a year or two before, so the imbalance that had char­ acterised years six and seven, when the boys had been children and the girls young women, often a whole head taller, now evened itself out. ‘Lovely to see you all!’ I said. ‘Did you have a nice holiday?’ A few mumbled in the affirmative, some nodded, others sat doodling in their own world.

‘Did you?’ Sindre said, and let out an unmotivated laugh. ‘I did indeed. We were in Crete.

Interesting place. Have you ever heard about the man from Crete who said that all men from Crete were liars?’ ‘Why did he say that?’ said Sindre. ‘Are they?’ ‘The man who said that was called Epimenides.

He lived two and a half thousand years ago. Why do we still remember what he said? Because it’s what we call a logical paradox. If what he said is true, then he’s a liar, which means it’s false.

In which case it’s true! Do you follow? And, if it’s true, then it’s false! And on it goes into infinity.’ They gawped at me. I smiled and went over to my desk, sat down and took out the r.