The deceptively fragile appearance of the house makes it appear at first an impractical invention for a land faced with recurrent earthquakes. Yet its lightness and flexibility, like those of a judo expert, actually contribute to its safety. Part of the reason is its foundation, which "floats" with the earth rather than being anchored rigidly. The traditional house is not held up by walls but by stout columns, almost a half-foot in diameter, embedded at their base in niches sunk into large, individually placed stones which are only partially buried. These columns reach through the house to the ceiling, whose weight secures them in their precarious foundation. In ordinary houses, the roof is a steeply sloping, four-sided pyramid whose light underframe is covered with multiple layers of shingles made from the tough bark of the _hinoki_ tree. A second set of shorter posts, similarly supported bv partially buried stones, holds up the platform that is the floor, a wooden deck of closely fitted planks set about two feet above the earth. The outer perimeter of the flooring becomes a veranda or walkway, called the _engawa_, and the inner space is partitioned into rooms by light walls of paper, plaster, and wooden grillwork. The outer walls of the house, which serve no structural purpose, are sliding latticework panels called _shoji_, which are covered with translucent white rice paper, bathing the exterior rooms in a soft daytime light. The _shoji_, ordinarily installed in pairs approximately six feet high and three feet wide, unite rather than divide the interior and exterior; during the summer they slide open to provide fresh air and direct communication with the outdoors. If greater insulation or safety is required, a second set of sliding panels, or _amado_, similar in appearance to Western doors, may be installed outside the _shoji_. Between columns too narrow to accommodate a pair of _shoji_ there may be a solid wall consisting of a two-inch-thick layer of clay pressed into a bamboo and rice-straw framework and finished inside and out with a thin veneer of smooth white plaster. Similar walls may be built inside the house where appropriate, and they and the columns are the house's only solid surfaces. The dull white color and silken texture of the plaster walls contrast pleasantly with the exposed natural grain of the supporting columns. Interior rooms are separated by partitions consisting of light wooden frames covered in heavy opaque paper, often decorated with unobtrusive designs. These paper walls, called _fusuma_, are suspended from tracks attached to overhead crossbeams. They slide to form instant doorways, or when removed entirely, convert two smaller rooms into one large apartment. _Fusuma_ provide little privacy between rooms except a visual screen, and it is rumored that this undesired communication increasingly inhibits lovemaking by modern parents.