Not that we spring to our feet each morning wailing “Carpe diem!” but the deep-seated knowledge that there are just so many mornings when we will rise at all instills an intuitive calculus of value, one that would be very different in a world with unlimited do-overs. The explanations we give for the subjects we study, the trades we learn, the work we pursue, the risks we take, the partners we join, the families we build, the objectives we set, the concerns we entertain—all reflect the recognition that our opportunities are scarce because our time is limited.
