I am a lucky man. As an Oxford don, I teach in one of the world's great universities. My subject is Classics, my department is the largest in its field in the world, and probably the best. My pupils are bright, keen to learn and argue, and sometimes brilliant. In Oxford, I work in beautiful surroundings. So why am I off to an American university for a year and perhaps for keeps? Part of the answer may be the natural desire for change. But I have been surprised to find how many of my colleagues are thinking about crossing the Atlantic, or are prevented only by compelling domestic reasons, like their partner's job or their children's schools.