in theory to, we hope, a good book in practice. Thanks to Rick O’Neil, Jack Furlong, Ellen Cox, Mark Moorman, Randall Auxier, Bradley Monton, Avery Kolers, Tom Flynn, and Saul Kutnicki for their help with various entries as well as to the anonymous reviewers for their thorough scrutiny of the text. We are also thankful for the work of Peter’s secretary, Ann Cranfill, as well as of many of his colleagues for proofreading. Robert E. Rosenberg, Peter’s colleague in chemistry, exhibited extraordinary generosity in reviewing the scientific content of the text. We would also like to express our appreciation to Manish Luthra, Marissa Koors, Liz Wingett, Daniel Finch, Rachel Greenberg, Aneetta Antony, and Caroline McPherson at Wiley for their careful and supportive editorial work. Thanks also to Peter’s students for their feedback, as well as for corrections and suggestions for improvement sent to us from several readers. Our enduring gratitude goes to Peter’s spouse and children – Catherine Fosl, Isaac Fosl‐van Wyke, and Elijah Fosl – as well as to Julian’s partner, Antonia, for their patient support.