‘Oxford.’ She pushed a loose strand of hair from her forehead. ‘Pembroke College.’

Clever girl. He should have guessed. ‘And what are you studying at Oxford?’

‘Philosophy and French.’

An interesting combination. Though he couldn’t help wondering what she planned to do with her degree. There wasn’t much call for philosophers these days.

‘You can’t study the great philosophers in translation,’ she said, as if guessing his thoughts, ‘and I already know German.’ She plucked at a thread on her sleeve. ‘My dad says I should study something more practical. He’s always banging on about job prospects. He works in the City and thinks philosophy is a ridiculous waste of time. It doesn’t help that he’s American. Always focused on the money angle.’

A Yank father in finance. He could imagine how that might be a challenge to a sensitive girl, and he couldn’t help but wonder how she’d ended up in a place like this. Perhaps a boyfriend had broken her heart, and she’d done something stupid. An overdose of pills? No scars on her wrists that he could see, but he’d witnessed enough romantic angst amongst the shifting sea of undergraduates at St Catharine’s to know that a dramatic gesture could take any number of forms. Or perhaps love had nothing to do with it. An overdose of philosophy could just as easily be at the root of her sorrow. Kierkegaard, that gloomy Dane, and certainly not his favourite philosopher as he’d professed in Copenhagen, would drive anyone to despair.

‘I was looking at the fish in that pond over there,’ she said, pointing at the shallow, rock-filled pool a few metres away. ‘One of them looks different than yesterday. Do you think they can change colour, like chameleons?’

Vidor considered this. He’d never taken much interest in the fishpond. ‘Possibly,’ he said, ‘though I’m not a specialist in fish. It’s probably your eyes playing tricks on you.’

‘Tricks?’ She showed a spark of life. ‘Why would they do that?’

He plucked a dried blossom from a nearby bush and crumpled it in his hand. ‘It’s not our eyes that see, but our brain. What we take to be reality, or a true representation of the world,’ he said, gesturing at the valley below, ‘is nothing but a construction of the visual cortex.’

She gave him an odd look. ‘That can’t be right. When I close my eyes, I see nothing, when I open them, the world appears. What I see…’ she pointed at the bronze fountain, ‘you see too, right?’

Rather than reply, he tore a blank page from his notebook and drew two small circles a few inches apart. He held it up to her. ‘How many circles do you see?’

‘Two, of course. How many do you see?’