This book began as a short story I’d written in 1985. I am very thankful for the guidance I received back then by members of the Cambridge Science Fiction Workshop (Jon Burrowes, Alexander Jablokov, Geoffrey A. Landis, James Morrow, Resa Nelson, Steven E. Popkes, Charles Ryan, David Alexander Smith, and Sarah Smith) and by Gardner Dozois, then editor of Asimov’s.