We are grateful for the feedback on this project at multiple stages from Samuel Baker, Caleb Cohoe, Bolesław Czarnecki, Trent Dougherty, Emma C. Gordon, John Greco, Josh Habgood-Coote, Stephen Hetherington, Anne Jeffrey, Lorraine Keller, Kevin Meeker, Andrew Moon, Jesús Navarro, Duncan Pritchard and Jason Stanley. We owe a special debt of gratitude to Stephen Hetherington for his wise guidance throughout this project.