He thinks, if you were born in Putney, you saw the river every day, and imagined it widening out to the sea. Even if you had never seen the ocean you had a picture of it in your head from what you had been told by foreign people who sometimes came upriver. You knew that one day you would go out into a world of marble pavements and peacocks, of hillsides buzzing with heat, the fragrance of crushed herbs rising around you as you walked. You planned for what your journeys would bring you: the touch of warm terra-cotta, the night sky of another climate, alien flowers, the stone-eyed gaze of other people's saints. But if you were born in Aslockton, in flat fields under a wide sky, you might just be able to imagine Cambridge: no farther.