"A Life in Art: Alma Thomas, 1891-1978," is precisely the right title for the current exhibition of Thomas' works at the National Museum of American Art.

Thomas really did live her life "in art." She will be remembered for the beautiful paintings she began to create when she was 75 years old--75!--but in the years up until then there hardly was a time when she wasn't painting or teaching or looking or getting intensely involved in art in some way or another.

She was the first student to enroll in the fledgling fine arts department established at Howard University by Prof. James V. Herring in 1921, and she was the first to complete the course--Howard's only fine arts graduate in 1924. For the next 35 years, from 1925 to 1960, she taught art at Shaw Junior High School. In 1935 she organized the Marionette Club in Washington. In 1938 she organized the first gallery of art in the D.C. public school system. In 1943 she helped Herring and Alonzo Aden to found the Barnett-Aden Gallery.

The list goes on and on, and yet it should be emphasized that Thomas never stopped looking at art or making it. She haunted museums in Washington and New York. She learned from the old masters but she also had an eye for the new. Apparently she couldn't pass by a good art book without buying it--her row house on 15th Street, where she lived and painted from the Howard days until she died, was stuffed with well-leafed volumes, old and new.

In the 1930s she got deeply involved in puppetry, both as teaching tool and artistic expression, and she received a master's degree in education from Columbia University with a thesis on marionettes. In the late 1940s she drew and painted from the model with members of "The Little Paris Group" founded in Washington by Lois Mailou Jones. In the 1950s she studied painting at American University, then the home of the most experimental of the college art departments in the city. Jacob Kainen, one of her teachers there, remembers Thomas as "an artist, not a student."

So, one does not have to tidy up the facts to interpret most of Thomas' life as an apprenticeship for the day when she could turn her full energy to painting--probably the longest art apprenticeship in history, an amazing true story.

Why she waited so long is an interesting question. Merry A. Foresta, the NMA assistant curator who organized the exhibition, points out that Thomas' fierce dedication to her teaching role played a part. When asked about it by Adolphus Ealey, who contributes a perceptive remembrance to the catalog, Thomas responded thoughtfully:

"Who knows? I'm an artist, not an analyst . . . Maybe I would have become an artist sooner if I'd grown up in Harlem instead of Washington. You know how reserved the black community here was in the old days, how it admired successful black people. Well, my family succeeded in Georgia, right in the heart of the South, and they did better than most after we came to Washington. I was proud of them and still am. But for educated young black people there were so many expectations then, so many pressures to conform. I don't know why I never lost this need to create something original, something all my own."

Teaching was the way Thomas paid her way and responded to the pressures but somehow she never lost the kernel inside that made her want "to succeed on my own terms, as a woman, an individual." Throughout those years she kept an eye on a definition of success that was not synonymous with conformity and the way, clearly, was painting. At age 69, when she finally left Shaw, Thomas was ready to begin.

From the earlier works in the show--tiny ceramic sculptures and a wonderful marionette--we can see Thomas was blessed from the beginning with talent and a good eye. In her serious, thoughtful work of the 1950s Thomas began trying on different guises, reflecting her associations with the Lois Jones group and the AU painters. A larger selection of transitional watercolor paintings from the late '50s and early '60s would have been welcome, but even so the exhibition justifiably focuses on the signature works she began to make in 1966, the year James Porter offered her a retrospective show at Howard.

Thomas said she was challenged by this invitation to "produce something significantly different, something diferent from anything I'd ever seen, different from anything I'd ever done." The result was a series of "earth paintings" that established the artist's mature style: abstract geometric patterns constructed with a sequence of mosaic-like brush marks of extremely bold colors.

These paintings approximated Thomas' profound response to the profusion of beauty in the natural world--the resplendent order of flower beds, the magical flickerings of light through leafy trees. When she began making them Thomas was inspired directly by the patterns of light and shade cast on her floor and walls of her kitchen from a holly tree outside. She started by "copying" these evanescent patterns and in the process transformed them into a strikingly fresh artistic structure.

The metaphorical nature of Thomas' paintings can be overemphasized. The paintings do indeed involve her impressions of the natural world--as direct as the holly tree by the window or as distant as her recollections of sunsets and brilliant roses near the hilltop home of her Georgia girlhood. Even more clearly, however, they involve her absorbtion in the specific problems of painting--they are so carefully, subtly and beautifully painted--and her lifetime of looking at art, intensely and knowingly.

One of the remarkable things about the work is the number of artistic associations that come to mind in front of the paintings without destroying their original force. Murky blue abstract expressionist paintings of the late '50s recall the romanticism of Albert Pinkham Ryder; her structures suggest Signac and Cezanne; her stripes bring to mind Gene Davis; her circles suggest Kenneth Noland; her colors can remind of Delaunay, her light of Whistler.

And yet the paintings are never less than Alma Thomases. There is probably something of her mother's stitchwork in them, and Byzantine mosaics as well. Once she took hold of it, she never lost the capacity to surprise. The works of her final two years employ an increasingly complex set of abstract markings and a new, sophisticated syncopation. They aspire to the abstraction of music. The title of one of them, a hard-hitting, magnificently expansive red-on-white triptych, sums up a lot about the aspiration and achievement of Alma Thomas: "Red Azaleas Singing and Dancing Rock and Roll Music."

The exhibition continues through Feb. 28. On Jan. 30 the museum will host an all-day symposium in its granite gallery on Thomas' life and art, beginning at 10 a.m. Tickets are required and free and may be picked up at the NMA's lobby desk at 8th and G streets NW.