Thomas Hart Benton, a champion of American regional art

No one disliked modern art more than Thomas Hart Benton. He blasted away at it whenever he could -- with no holds barred. And since he was very handy with words -- both spoken and written -- what he had to say about it made quite an impact in the 1930s and 1940s.

What not many people knew, however, was how deeply he himself had been involved with modernism as a youngster. We knew he had dabbled a bit with it in Paris between 1908 and 1911, that he had experimented with it in this country for a while in the 1910s, and that he had then turned his back on it once and for all in the early 1920s to become one of the great champions of American regional art.

But we didn't know how seriously he had tried, as a young man, to find his painterly voice through one or another modern style -- and how really promising he had been as a potential modernist.

We know a bit more about that now. A goodly number of Benton's early modernist works have just resurfaced -- and are on display at the Salander-O'Reilly Galleries here.

The story of how that all came about is an interesting footnote to recent American art history.

As is commonly known, Jackson Pollock was a student of Benton's. Less well known is that Pollock's older brother, Charles, was also a student of his at New York's Art Students League. In 1929 Charles, who had sublet Benton's apartment for the summer, found a suitcase full of his teacher's early paintings and sketches in a closet. Benton told him to keep them, and Pollock did -- until this year, when the paintings and sketches were obtained by the Salander-O'Reilly Galleries.

For those five decades, this historically important collection of early works by Benton remained essentially unknown and untouched -- and most assuredly, unexhibited.

What these small and very colorful paintings tell us (the pencil sketches included in this find will be exhibited in the spring of 1982) is that Benton was as fascinated by Cezanne and the cubists as were most of the advanced younger painters of his day. And that he had a special interest in synchromismcq , the only early modernist movement of any quality originated by Americans.

Synchromism was the brain-child of Morgan Russell and Stanton MacDonald-Wright, who joined forces in Europe for a short period in the very early 1910s to paint abstracted painterly visions entirely through color. Benton was heavily influenced by this movement and even exhibited with its founders in New York in 1916.

That synchromism was pretty much to his taste is revealed by several of the paintings in this exhibition - especially those that let him exercise his natural inclination for baroque spacial configurations and for hot, passionate color. Such works as ''Flowers,'' ''Still-Life,'' and ''Landscape No. 5'' are wonderfully concise and yet lyrical statements in which color drives home each picture's expressive point much the same way a hammer blow sends a nail deep into wood. And the various ''abstractions'' indicate how seriously Benton probed the mysteries of color -- especially those that permit color to open up and expand space while remaining perfectly flat in appearance.

Of the 49 paintings on view, only six or seven could by any stretch of the imagination be easily identified as Benton's. And those give him away only because of his typical swirling approach to landscape and his way of drawing the human figure.

The rest could have been done by almost anyone with the proper amount of talent and imagination. That very possibly is what ultimately caused Benton to forsake this particular approach to painting. He was a passionate individualist -- anyone who knew him in later years understood perfectly why he and Harry Truman got along so well -- and modernism, he must have felt, simply didn't give him the opportunity to exercise that individuality.

He was also a dedicated and idealistic American, the great-nephew of the first US senator from Missouri (his namesake), and the son of a member of the US House of Representatives, Maecenus E. Benton. This country was his home. It was also, he decided in the early 1920s, what he was going to paint from then on. In pictures that would be recognizable and familiar to the farmers and small-town folk he was going to depict.

Small wonder then that he later became so violently opposed to international modernism. Not only did it deny that what he was painting from 1925 on was art, it also must have reminded him of his younger, more bushy-tailed days when everything had seemed possible.

This is a fascinating show for anyone the least bit interested in the evolution of 20th-century American art. The paintings are very small and most of them would have to be categorized as studies. But they are exciting nonetheless.

The gallery has also included a few examples by contemporaries of Benton to round out the picture of the 1915-1920 period. Included here are excellent works by Charles Demuth, Morton L. Schamberg, Marsden Hartley, Morgan Russell, Stanton MacDonald-Wright, Konrad Cramer, and Arnold Friedman.

This valuable exhibition will remain on view through Jan. 30.