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
The details of a building cannot be made alive when they are made from modular parts
If the builder wants to build the room from modular four-foot panels, he must change the size of the rooms, and change their shape, to fit his panels.
In such a building system, it is impossible for a person to create a plan which reflects the larger subtleties of site or plan. Each plan will always be chopped and disfigured to make it fit the building details.
To make the building live, its patterns must be generated on the site, so that each one takes its own shape according to its context.