I have recently wasted two days on a not‐so‐good book. It’s not the 5 or so hours that I spent reading the not‐so‐good book that I regret. It’s the time I spent trying to decide what to write about the not‐so‐good book, indeed whether to write about it at all. Time spent reading (almost?) anything isn’t wasted. Even if all I learn from a book is what the not‐so‐good thinking on a particular subject looks like I have gotten some value for my time. The time I spent thinking further about the not‐so‐good book, however, is time that I could have spent thinking about something more interesting.