They also serve who sit and wait

At first, their work was called "ugly and repulsive." When they persisted, critics dismissed them as mere "Impressionists," a label Degas found continually irritating. The Paris Salon rejected them until they stopped applying.

Now, of course, these lush images from the late-19th century are the staple of calendars and handbags. Such is the price of success. The water lilies of Giverny seem as familiar and stirring as the Magic Kingdom of Orlando.

Mary Cassatt, the only American in the small group who called themselves "Independents," has fared no better. She once said, "I hate conventional art," but now her paintings of mothers and children make sweet greeting cards.

Seventy-five years after Cassatt's death, a little novel by Harriet Scott Chessman may wash away the saccharine patina that's grown over her work.

The story is told by Mary's dying sister Lydia, the subject of several memorable paintings that are reproduced in this beautiful book. Their father, a wealthy Pennsylvanian, has brought the family to Paris, where his wife can care for Lydia and keep an eye on Mary until, it's hoped, she gives up this art folly and finds a husband.

Chessman has matched her style to these paintings in a way that enriches both. The story lulls through the last three years of Lydia's life, in a series of sensitive impressions of the Cassatts' apartment, Mary's studio, and the park.

Seven Stories Press and The Permanent Press teamed up to produce this novel with five color plates and liberal white space to set off the short scenes and dreamy introductions. In fact, like the paintings, it's so pretty that it risks looking more precious than it really is.

In the conventional sense, nothing much "happens" in this story. There's no dark scandal behind Cassatt's work, no Mommy Dearest lurking outside the frame of those famous maternal images. Mary is a vibrant, kind person, devoted to her sister and favorite model. The family leads a life of serene leisure.

Yet Chessman gently pushes us beyond the pastel taffeta into the folds of Lydia's despair. Her doctor has outlined the discouraging course of the disease that will soon take her life, but her fear is overshadowed by a deeper sense of anger at this cruel abbreviation. The world she cannot enter looks frustratingly colorful and exciting.

Convinced she's "as plain as a loaf of bread," Lydia can hardly believe that Mary's interest in painting her is sincere. "Who is this? I ask myself, for I can't think it's me, and yet I know, with exquisite pleasure, that it is."

How delicately, how perfectly Chessman considers the subtle currents of love and jealousy that mingle in this sibling relationship. She's particularly sensitive to the unmentionable resentments that stretch between the sick and the healthy. As Mary's reputation increases, Lydia fears being left out of the picture even before she dies.

Degas, her sister's acerbic friend, intimidates her, and yet he's the one who finally prods Lydia

to consider her own creative contribution to these remarkable paintings.

In one of the novel's most poignant moments, she realizes what her sister is giving her in return. "On her canvas," she thinks, "I become a healthy woman in blue and white ... in a world apart from the sting of bees and sickness, mortal life." It's a realization that could be easily overplayed with metaphysical sentimentality, but Chessman keeps the tension tight between Lydia's fierce love for life and her calm acknowledgment that she's leaving it behind.

"Terrible," she thinks, "to imagine a world continuing beyond my own dissolving, yet what if I am a presence for Mary, and for others too, leaving a trace? Maybe I should not be so afraid of vanishing, after all."

In Chessman's compelling story, Lydia's hopes are confirmed, and her sister's paintings seem more alive than ever.

Ron Charles is the Monitor's book editor.

Lydia Cassatt Reading the Morning Paper

By Harriet Scott Chessman

Permanent Press/ Seven Stories Press

164 pp., $24