The "modern" style is based largely on "De Stijl."

An art revolution, an art form and a cult, De Stijl flourished in the Netherlands between the two world wars. Its most famous exponent, at least in this country, was Piet Mondrian. But there was more to the group's work than black bars and prime-colored squares. By itself as well as via the German Bauhaus, the De Stijl group decisively influenced virtually everything around us, from the Kleenex box to the Martin Luther King Library and highrise office slabs.

A documentary exhibition of some 30 panels, a sort of survey course of De Stijl prepared by the Netherlands' Ministry of Culture, opened yesterday at the Pension Building under the auspices of the Committee for a National Museum of the Building Arts.

De Stijl was the idea of Mondrian, architect-painter Theo van Doesburg and a dozen or so other Dutch artists. They wanted to carry Braque and Picasso's Cubism a step further and reduce the representation of nature to the straight line and right angle (the horizontal and the vertical), the three primary colors (red, yellow and blue) and the three non-colors (black, gray and white).

Try as one might -- and thousands of art historians have tried in laborious dissertations -- it is impossible to define just what possessed these artists to pursue this idea with such tenacity. They felt, much like the Russian Constructivists and the artists of the Bauhaus, that the "degeneracy" of Victorian art had intellectually bankrupted all art as we knew it -- that art had to start at the very beginning, as it were; that it had to be disembodied into pure abstraction.

In 1917, when the De Stijl group was founded, the western world was in the throes of a fierce war that seemed to destroy all historic precepts and values and seemed to some -- particularly the neutral Dutch -- as the cataclysmic birth of a totally new age. Virtually all European artists, including Russians like El Lissitzki, saw it as the age of science and technology which would bring about a perfection of which human hands were not capable and in which the individual and individual creation would be fused into an all-encompassing utopian collective.

Some dissertations on De Stijl theorize that the simple geometric forms were inspired by the largely man-made, geometric "polder" landscape with its straight ditches and flat square fields the Dutch have wrung from the sea. Perhaps.

But I should think that if Mondrian had wanted to paint fields as seen from a church steeple he would have painted fields as seen from a church steeple. He was not a timid man. What he and his group wanted was to distill art to its very essence. They wanted to find a formula, as Mondrian put it, "of universal harmony."

And universal harmony was not just to be painted on walls -- it was to be universal. That is why De Stijl, from its very beginnings, turned to architecture and the design of furniture and other artifacts. We were to live in pure form.

The show at the Pension Building presents houses, chairs, interior furnishings, posters and billboards and utopian cities that come fearfully close to the housing projects and downtown centers that have actually been built in the past few decades all over the world.

The main impetus for this brave new bare and square world came from the Bauhaus. the German art and design school headed first by Walter Gropius and then by Mies van der Rohe. But aside from Mies' personal genius, the Bauhaus did not create a style of its own. It synthesized the related styles of its time -- Constructivism, Le Corbusierhs work and De Stijl. It did so despite itself.

When Theo van Doesburg asked Gropius to be allowed to teach at the Bauhaus in Weimar he was indignantly refused. But Doesburg ventured to Weimar just the same, lecturing in an inn near the Bauhaus. He emptied Bauhaus classrooms and filled the Bauhaus minds with his ideas.

The De Stijl show, which runs until March 16, is the first of a number of architecture exhibitions the Committee for a National Museum of the Building Arts plans to mount in the Pension Building as a prelude to opening a museum there.

Last November, the committee's proposal for an exhibit, information and public education center on architecture, city planning and building construction was adopted by Congress. A Joint Resolution asked the General Services Administration, the National Endowment for the Arts and the Smithsonian Institution to comment on the idea by March.

Public hearings on the proposal are expected later this year. The Pension Building, which now serves as temporary headquarters of the Heritage Conservation and Recreation Service, is located at 5th and G Sts. NW, directly at the Judiciary Square Metro station. The exhibition is open from 9 a.m. to 5 p.m.