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 roji, the garden path which leads from the machiai to the tea room, signified the first stage of meditation—the passage into self-illumination. The roji was intended to break connection with the outside world, and to produce a fresh sensation conducive to the full enjoyment of aestheticism in the tea room itself. One who has trodden this garden path cannot fail to remember how his spirit, as he walked in the twilight of evergreens over the regular irregularities of the stepping stones, beneath which lay dried pine needles, and passed beside the moss-covered granite lanterns, became uplifted above ordinary thoughts. One may be in the midst of a city, and yet feel as if he were in the forest far away from the dust and din of civilization.
...Thus prepared the guest will silently approach the sanctuary, and, if a samurai, will leave his sword on the rack beneath the eaves, the tea room being preeminently the house of peace. Then he will bend low and creep into the room through a small door not more than three feet in height. This proceeding was incumbent on all guests—high and low alike—and was intended to inculcate humility.