He was Paul Cezanne's companion and Vincent van Gogh's idol, and his odd, encrusted pictures-unlikely as it sounds-link the thickly brushed abstractions of New York action painting with the fliratious and courtly fantasies of 18th century France.

Adolphe Monticelli (1824-1886) was a most peculiar painter and a most peculiar man. He claimed he could see souls (they looked like colored flames), often spoke with God, and said he had known Titian in a previous existence.

Those who think art history should be linear and logical trip on Monticelli. He jumps out of their cubbyholes. How could one man influence painters as diverse as van Gogh, Chaim Soutine and Albert Pinkham Ryder? Where does one place pictures that are, like Monticelli's, both avant garde and old-fashioned?

Monticelli didn't fit-at least before Aaron Sheon, the Pittsburgh art historian organized the exemplary exhibit that opened last night at the Corcoran Gallery of Art. "Monticelli: His Contemporaries, His Influence" is a revisionist exhibition. It adjusts our un derstanding of late 19th-century France.

Most textbooks treat the period as a time of battle. On one side are the good guys-Manet, Cezanne, van Gogh-who led art toward abstraction while their dull opponents, oblivious to progress, rehearsed stagnant themes. But Adolphe Monticelli fought on both sides at once.

His wild, patterned brush strokes, unearthly colors and avoidance of sharp focus please friends of the modern who prefer to ignore the scenes he chose to paint. In fact, there is nothing at all new about the knights, nymphs and dryads who flirt with one another in Monticelli's dappled glades. His garden scenes are as sweetly scented as the rococo romances painted by Watteau.

These densely painted pictures, so daring in technique, cast light on the terra cotta lovelies sculpted by Rodin and on the naked bathers painted by Cezanne. How could men so modern address themes to antique? The Monticellis here suggest at least one answer: the conflict between old and new is more of our age than of theirs.

"I am painting for 50 years in the future. It will take that long for people to see my painting," said Monticelli, yet in almost every picture he celebrates the pleasures of an imaginary past.

He was a good friend of Cezanne's. The two men would spend weeks with their easels and their sketchbooks, wandering the country roads of their native Provence. Van Gogh never met him, but he collected Monticellis and, following his idol, set out in his last years for the South of France.

"I owe everything to Monticelli, who taught me the chromatics of color," wrote van Gogh. "He was a strong man-a little cracked, or rather very much so-dreaming of the sun and of love and gaiety . . . a thoroughbred man of a rare race, continuing the best traditions of the past . . . Now listen: for myself I am sure that I am continuing his work here, as if I were his son or his brother."

Adolphe Monticelli was born in Marsille, the illegitimate son of an obscure civil servant. His parents, who finally married when he was 10 years old, conversed in the Provencal dialect and spoke little French. Monticelli studied art in the academies of Paris but when, in 1870, the Prussian armies came and the Second Empire fell, he walked south to the sea.

His pictures at the end grew wilder and wilder. At first one hardly sees the figures in his dappled forests of pure paint, but they are almost always there. Monticelli, Sheon shows us, was as loyal to the spirit of the Rococo Revival as he was to exploring the emotional possibilities of color. Sometimes, working out of doors, he could be heard to shout "God, it's beautiful," as he applied his paint.

Though he died in relative poverty, his odd fantastic pictures were briefly in demand in the first years of this century. Sen. William A. Clark of Montana left 21 "Monticellis" to the Corcoran. Sixteen of these paintings, now on view in the corridor, are however imitations, forgeries, or fakes. The exhibition closes May 27. CAPTION: Picture 1, "A Dream of Woods and Sunlight," by Adolphe Monticelli.; Picture 2, "Under the Tree at the Edge of the Water," 1885, detail.; Picture 3, Adolphe Monticelli.