He plucked up his courage to challenge her. 'What are we doing here, Julia? What do you want?'

She laughed, a throaty sound. She was twenty-eight, three years older than he was; her age showed in her voice. 'That's not a very nice question. What do you think I want?'

'I don't know yet. Something to do with Godel. You used me to get you in here, didn't you? Into this study.'

'Can you blame me for that? Kurt Godel is the world's greatest logician. He's building a new mathematics, so they say. Or dismantling the old. Something like that, isn't it true?'

'You're a historian. You're attached to Princeton University, not this institute of math and physics. Why would you care about Godel?'

'You're ever so suspicious, aren't you? But those suspicions didn't make you fight me off. He's such a funny little man, isn't he? Short and shabby with that high brow and his thick glasses, scuttling like a rabbit in his winter coat.'

'He's been known to take lovers among his students. Despite his unprepossessing looks. I mean, he's still only in his thirties. Back in Vienna-'

'The first time I spotted Godel he was walking with Einstein. Now you can't miss Einstein, can you? Do you know, he was walking in carpet slippers, out in the middle of the street! Is he friendly with Godel, do you know?'

'They met in 1933, I believe. Friends – I don't know. Einstein is the most exotic of the European beasts here in this American zoo, I suppose. But even Einstein had to flee Hitler.'

'Ah, Hitler! I've been in his presence, you know.'

'Whose?'

'Hitler's. I shook his hand. I wouldn't claim to have met him, exactly; I doubt he remembers me at all. I was an exchange student. I wanted to see for myself what the Germans were up to, rather than swallow the usual horrid propaganda. The transformation of that country from economic ruin in just a few years is remarkable. They made us very welcome. Hitler has a very striking presence; he has a way of looking through you. Goebbels, on the other hand, pinched my bum.'