'The past, if there is such a thing, is mostly empty space, great expanses of nothing, in which significant persons and events float. Nigeria was like that for me: mostly forgotten, except for those few things that I remembered with outsize intensity.' Along the streets of Manhattan, a young Nigerian doctor doing his residency wanders aimlessly. The walks meet a need for Julius: they are a release from the tightly regulated mental environment of work, and they give him the opportunity to proces ...