To think about Frank Lloyd Wright is one thing, but to stand in one of his rooms with bright afternoon sunlight cutting sharply through the warm shadows of the place is altogether another -- an experience that for one enlightening moment makes Wright's complex greatness seem wordlessly clear.

To provide such moments is one of the fundamental reasons for our great museums, so the recent opening at the Metropolitan Museum of Art in New York of a complete living room designed by Wright, sensitively installed and as true to the architect's original intentions as scholars could make it, is an event worth celebrating.

The room comes from a large summer house overlooking a lake in Wayzata, Minn., commissioned by Francis W. Little in 1912, although not completed until about a decade later. The room's very existence today is a sort of triumph. Following the adamant wishes of the Littles' daughter, the house in which it was the centerpiece was demolished a decade ago, but not before the Metropolitan, alert to an unlikely opportunity, stepped in to purchase its entire contents.

These were then dismantled piece by piece and labeled, crated and stored to await completion of the museum's new American Wing, where the living room has been painstakingly reconstructed and tellingly placed with one of its walls facing an open knoll in Central Park. In the meantime, other parts of the interior have been sold to other public institutions -- the library to the Allentown (Pa.) Art Museum and other pieces to a museum in Karlsruhe, Germany -- so that the huge Little house is now literally spread in pieces across the globe. (Of the major ensembles only the master bedroom remains to be placed.)

To accompany the long-anticipated opening of the reassembled room, the Metropolitan has put on view its large and varied array of Wright material, including furniture from many of his most important buildings and a selection of plans and perspective renderings. In Washington the Lunn Gallery (406 Seventh St. NW) has put together a similar exhibition of Wright's furniture, fixtures and plans, and also of related materials by other architects.

The three exhibitions make an extraordinary tribute to Wright, focusing especially upon his achievements during the first decade of this century, when he conceived the innovative designs of his prairie houses. The major unifying factor in the prairie house designs was Wright's handling of space--those extraordinary, asymmetrical, longitudinal floor plans combining enclosure and openness in unpredictably equal measure and, on the outside, those massive interconnected horizontal planes with their plentiful window courses and broad overhanging eaves.

Wright's prairie house floor plans had the most far-reaching consequences, from their impact upon European modernists, such as the de Stijl group and Ludwig Mies van der Rohe, to the open-plan "split-level" homes that proliferated in the American suburbs through the 1950s and 1960s. It is significant that both the Lunn and the Metropolitan exhibitions draw heavily upon the unusual portfolio of prints, containing plans and perspectives from about 70 Wright buildings and projects spanning the period 1893 to 1909, that was published by Ernst Wasmuth in Berlin in 1910. Every European architect of note had ample chance to study these drawings and, as the history of architecture shows, many took full advantage of the opportunity.

It is the living room of the Little house, though, that indelibly brings it all together, showing, in a way that separate pieces simply cannot, the wholeness of Wright's imagination and the interrelatedness of his many design activities. A single room of course is no substitute for the whole thing, for the rooms and house together in the precise places Wright intended, but the Met's installation of the Wayzata living room, open on two sides, goes a far piece toward overcoming this unavoidable problem.

More important, it unequivocally demonstrates the other secret of Wright's best residential designs: his mastery of details. The room is all of a piece in things large and small, from the hipped ceiling with its beautifully paneled stained-glass lights, to the deep double tiers of light-oak wall molding that envelop the entire room, to the floor, chairs, tables, flower arrangements and even to exquisite lamps attached to the walls in just the right places.

The room is unquestionably Wright's -- all Wright's. The Littles didn't necessarily like it that way and furnished it a bit differently, we are told. Wright designed it with Mrs. Little's musical interests in mind, but the family did not commission the piano he designed for the room, although, as we can see from Wright's drawings for the instrument on display at the Met, it would have been an amazing, and indisputably Wrightian, piano. Wright was often impatient, not to say dictatorial, with clients who failed to live up to his vision, a craggy aspect of his mountainous personality that doesn't really detract from the richness of his achievement.

Wright was a maker of places as well as spaces, and nothing he touched was neutral. The Little house living room, at once airy and dark, spacious and solid, tells a lot about the uniqueness of Wright's architectural vision, its inimitable idiosyncracy, and at the same time suggests how he came to be so vastly influential: Whether dealing with a single window or a row of them, a dried blossom or a whole hillside site, Wright aimed at the heart of the matter and as often as not he hit it.

The Met is to be congratulated for its resourcefulness in saving the room and putting it back together again with such fidelity and craft. It will bring a large new audience into direct contact with the genius of Wright.

The room, of course, is on permanent display. The accompanying Met exhibition continues through Feb. 27. The Lunn show will remain on view through Jan. 15.