Henry held the lamp over the hole. In a moment Albrecht’s silver-grey head emerged from the chimney’s constriction, and shortly afterwards he hauled himself out to stand beside them.

‘Not the most comfortable route,’ he observed. ‘You have found no other way into this cave?’

‘No. I’m pretty sure there isn’t one. Caves that have paintings are normally difficult to get at. There are several which are much harder than this to reach.’

‘I did not know that. So even our prehistoric ancestors preferred to reach their really important goals the hard way? Folly has a long history.’

Henry led the way over to the painting of the bison. ‘This is my favourite. See the foreshortening effect with that slope of the spine away from the neck? They knew more about perspective than modern man did five hundred years ago.’

‘Yes. The flank is badly worn – by erosion?’

‘No, by spear jabs and arrows. That’s the magic part of it – to bring them success in hunting. The Australian aborigines still do it.’

‘And does it work?’

‘A good hunter is always likely to succeed, and the more confident he is the more successful he’s likely to be.’

‘That is certain.’ Albrecht flashed his own torch along the wall. ‘And this? A man?’

‘No. A bear.’

‘I see it. It is badly worn, though. They were fond of bear meat, our ancestors?’

‘It wasn’t only that. They had to share the caves with the bears. Even a good hunter would need a very heavy dose of self-confidence to be prepared to tackle a bear in a narrow tunnel underground. I should think they were very fond of bear meat; every mouthful would be a separate triumph.’