To build a folly is essentially to do something a second time, something at an inopportune moment. That something is always the memory of something forgotten, about which we can paradoxically say "There it is again."
Follies were misunderstood, purposeless constructions. They were often only small, extravagant gestures in a garden, easily whisking off the imagination to distant lands, a sort of time capsule built to awaken the memory and induce surprise in passers-by. They marked locations, organized secondary paths in a park, or simply predicted the arrival of better times—a demarcation, a sacred spot, a mysterious trail, a hill whose tragic rocky nature begged for a tower, a party, or the arrival of summer.
“It is demonstrably true that things cannot be other than as they are. For, everything having been made for a purpose, everything is necessarily for the best purpose.” — Professor Pangloss
Ugh, now I have to write this boring part, I would think. I would spend a few days in active rebellion against this directive that I imagined the book was imposing.
Then I would realize: this is my book! There are no rules! I can write it however I want! Also, I would think, if I’m bored by something that I believe I need to write, the reader undoubtedly will be too, if not because the subject is inherently boring, then because I myself find it so unbearably tedious to imagine discussing it for five pages. Often as not, I would remember some aspect of the subject that deeply interested me, something a little outside the way it’s usually perceived or written about. Then I would meditate on that, and soon I would be scribbling notes from an increasingly excited place until I found a way forward. A form of beginner’s mind.