I would like to thank all the people involved with this book, and with this trilogy. It has been a long and complicated undertaking. Now, at long last, it is complete. These three books would have been absolutely impossible if not for the prodigious literary output of the late Isaac Asimov, and if not for the prodigious popularity of his work. He is and will be greatly missed, and we are all in his debt. It has been an honor and a privilege to explore the ideas and the worlds he created. Thanks as well to the editors who have labored over Caliban, Inferno, and Utopia. David Harris, John Betancourt, Leigh Grossman, and Keith R. A. DeCandido all worked to improve these books-and all succeeded. Thanks also to Susan Allison, Ginjer Buchanan, and Laura Anne Oilman of Ace Books, to Peter Heck, and to Byron Preiss, for their labors on my behalf. And, of course, thanks as well to Eleanore Maury Fox. I hadn't even met her when I started work on this trilogy. Now she is my wife. This is the spot where authors usually talk about the love, affection, and patience of their long-suffering spouses, and Eleanore certainly deserves thanks on all those counts. But I also got something else: very hard-edged, straightforward, professional editorial advice. It helped a lot. I now come to my sister Constance Witte, my brother Chris Allen, my brother-in-law Jim Witte, and my sister-in-law Edith Allen. This last