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
Is there positive value to recognizing an invisible Design Concept as a real entity in design conversations? I think so.
First, great designs have conceptual integrity—unity, economy, clarity. They not only work, they delight, as Vitruvius first articulated. We use terms such as elegant, clean, beautiful to talk about bridges, sonatas, circuits, bicycles, computers, and iPhones. Recognizing the Design Concept as an entity helps us to seek its integrity in our own solo designs, to work together for it in team designs, and to teach it to our youth.
Second, talking frequently about the Design Concept as such vastly aids communication within a design team. Unity of concept is the goal; it is achieved only by much conversation.
Thus, moviemakers use storyboards to keep their design conversations focused on the Design Concept, rather than on implementation details.