Like all of us as we age, Christopher .de Hamel holds in his head a world of experience. But the work of synthesis he undertakes when he looks back on his life is more effortful for him than it might be for others, because he has to juggle hemispheres – those of his brain and those of the globe.

On the left side of his head, de Hamel is an academic bookworm, while the right side belongs to a wistful poet, and those separate cerebral regions correspond to two disparate locations on the map of the world. In the New Zealand of his youth, de Hamel dreamed of Europe, homeland of the illuminated manuscripts that were even then his passion. Now, in London after a long career as a bibliophile antiquarian at Sotheby’s and then Cambridge, he finds himself yearning for a New Zealand more easily reached in space than in time.

One view of migration today is that it is the last resort of the indigent and desperate, risking their lives in unseaworthy boats. De Hamel, shuttling to and from the ends of the earth, describes a more leisurely and privileged process. His English parents set sail for the Antipodes in