Is it possible to name the first true abstract pictures?Who painted them, and when, and what do they look like?

Among connoisseurs of breakthroughs, there has been for many years one agreed-on answer: Wassily Kandinsky, Munich, 1910. The Russian's first abstractions -- his grand "Improvisations" -- are lyrical and spiritual and wonderfully prophetic.

Kandinsky, claim the textbooks, "liberated painting from all imitative purposes." His "Improvisations" look as if the artist made them up in the act of painting them. He said they were "spontaneous" and that their "inspirations" were "largely unconscious," and we saw no need to doubt him. When he wrote that they portrayed "non-material nature," we took him at his word.

Now, however, it turns out that we were much misled -- not only by his champions, not only by his writings, but by his pictures, too.

"Kandinsky: The Improvisations," the beautiful exhibit that goes on view today at the National Gallery of Art, dares decipher those "first true abstractions" -- with astonishing results.

The "Improvisations," first of all, were not truly improvised, but worked up with great care. And they are not pure abstractions.When decoded they reveal not only colored forms, but churches, ghosts and sailing ships, smoking cannon, mounted knights, and scores of other mystical, half-concealed signs.

For more than half a century, since the critic Roger Fry first described them as "abstract," we have viewed these works though veils. This timely and mysterious show not only tells us much about the dawn of abstract painting. It tells us even more about the shifting critical conventions of our time.

One reason that we did not see the sails, swords and riders in the "Improvisations" is that we did not look for them. Modern viewers, who believe the growth of abstract art -- from Malevich and Mondrian through Pollock and Frank Stella -- a triumph of the spirit, have for years refused to ask, "What is that a picture of?" The question sounded foolish, insensitive and tasteless.

But Kandinsky's age was not our own. He was born, in Moscow, in 1866. A student of theosophy and a man in touch with mysteries, he gave up law for painting -- at the age of 30 -- at a time when seances were everywhere in fashion. In "On the Spritual in Art," the book Kandinsky published in 1911, he hinted he had glimpsed a new religion, "especially in painting." But he'd never left the old one. Deluges and serpents, "arisen souls" and churches, are there to be discovered -- if only by initiates -- in his "abstract" paintings.

"Today art is moving in a direction of which our fathers would never even have dreamed," wrote Kandinsky's friend Franz Marc in 1912 in Munich. "We stand before the new pictures as in a dream and we hear the apocalyptic horsemen in the air." Those apocalyptic horsemen thunder through this show.

Kandinsky, a sophisticate who had spent a year in Paris, was, by 1910, abundantly aware of the new inventions of the Cubists and the Fauves. In 1911, he noted in his notebook: "Matisse -- color. Picasso -- from. Two great signpoints pointing toward a great end." That "great end" was an art of nonrepresentation. In his "Improvisations" he approached the non-objective, but did not go all the way.

The National Gallery's show is the first exhibition devoted solely to the famous pictures in that series. Extending the research of many other scholars, research largely based on a series of small studies and preliminary sketches found in 1957, E. A. Carmean, the gallery's curator of 20th-century art, has managed to identify many of the strange motifs, the troikas and the lovers, the horses and the riders, the boats and ghosts and tumbling towers -- "signs and codes," he calls them -- that regularly recur in Kandinsky's abstract art.

Though the broad sword we see in "Improvisation 8," the smoking, wheeled cannon at the bottom right of "Improvisation 30," the sea battle we witness in "Improvisation 31" (a picture that the gallery bought three years ago) and the blue horse with yellow spots that dominates the center of "Improvisation 12" (a picture that was once owned by the painter's friend, Franz Marc) may easily be read, there are other signs within these works that are vastly more obscure.

Those tall standing rectangles, open at the bottom, are signs of drifting ghosts. And those three curving lines -- the troika -- represent, at once, the three-horse teams that pull the famous sleds of Russia and the apocalyptic horsemen that ride at the world's end. These forms, we feel, are meant to be sensed rather than read.

These paintings point a passageway not only toward abstraction, but to the viewer's soul. One great virtue of these pictures is that they gain in majesty, and in mystery as well, even when deciphered. Carmean, in recent years, has organized small shows on themes explored by Picasso and by Mondrian -- who now competes with Malevich, and with Kandinsky, too, for the elusive title of "the first abstract painter." No show he has mounted here is more beautiful than this one. It is on view in the East Building, and closes Aug. 2.