My first thanks go to my agent, Elyse Cheney, who encouraged me to undertake this project and provided invaluable, unstinting guidance in shaping it. Gratitude also to my editor, Ann Godoff, for giving me the freedom to find my voice, and to the staffs at Cheney Literary and Penguin Press, for all their creativity and care. Thanks as well to the friends who believed in the book along the way and who helped me believe in it, too. Two volumes were indispensable: Claire Tomalin’s biography and Deirdre Le Faye’s edition of the letters. My highest thanks go to Karl Kroeber, who started it all, and to Aleeza Jill Nussbaum, who gave me the perfect ending.