Yesterday marked a small, sad anniversary in Washington's history, one likely to pass unnoted by a city busy with its affairs and the oncoming holidays. One-hundred years ago, on Dec. 6, 1885, Marian Hooper Adams died in her house at 1607 H Street, N.W., near the present site of the Hays-Adams Hotel.

Marian Adams has to be instantly identified as the wife of Henry Adams, famous author and descendant of the Adams line that gave America two presidents. Like most women in the Gilded Age, Marian had few claims to fame herself. She was small and plain-featured, only modestly talented in the feminine arts of music or drawing.

But she had a quick mind and a lively, sharp way of conversing. In 13 years of marriage she and Henry made their home into Washington's most influential salon, where public figures met the nation's leading artists and scientists.

Men felt at ease in Marian's company, for she was bright and practical, never coy. Henry James liked her critical, ironic manner; Clarence King brought her souvenirs from his geological treks in the high Sierras. To intimates she was not Mary or Annie but Clover, a nickname that suited her artless manner.

A doctor's daughter, Marian took charge of his household at the age of 10, when her mother died. Unmarried at 29, she had not expected to wed, least of all to the brilliant Adams. But she did, to the disapproval of his aristocratic clan. Her line was tainted, the gossips said, by a deep strain of insanity.

The years of this marriage were crowded and difficult. Henry buried himself in work, striving to make his mark as an Adams. Marian read widely, but she lacked his appetite for power. They had no children. She took up riding, photography, the ritual life of a hostess. Every Sunday morning she wrote to her father, whom she missed with an awful foreboding: ". . . you must keep my place open and let me come into it again."

As she aged, Marian's bouts of depression became chronic. In the circle of gifted friends that swirled about her husband, she felt dull and trivial, merely functionary. Under a pseudonym, he published "Democracy," a novel that lampooned Washington society -- and covertly mocked his wife's brittle, neurotic temperament.

When her father died in the spring of 1885, Marian entered a steep decline. Henry tried to distract her with trips and plans for a new house, but his attentions were too late. As winter came on, gray and rainy amid the holiday tinsel, she reached her last Sunday morning.

On Dec. 7, 1885, The Washington Post reported that Adams found his wife unconscious and summoned a doctor who pronounced her dead: "probably died instantly from paralysis of the heart." The truth was too ugly for Adams to admit. Marian had drunk potassium cyanide -- a chemical used to develop photographs.

Adams was devastated, but he silenced his grief. If he felt any responsibility for her despair and anger -- for suicide is a denunciation, a rejection of pretenses -- he never said so. He destroyed his journals, her letters to him, and he omitted any reference to their marriage in his autobiography.

But Adams paid his homage to Marian with a grand, oblique gesture: for their mutual grave in Rock Creek Cemetery he commissioned a memorial by two of America's leading artists, Stanford White and Augustus St. Gaudens. Untitled and standing far from the tourist circuit, this monument draws a steady stream of visitors who come to contemplate its mysteries.

They find a grove of tall laurel trees and within this bower a bronze statue, resting on blocks of pale red granite. Years of weathering have turned the bronze to a blue-green, almost clay- like texture. The figure is seated, shrouded in deep folds of drapery, its face sheltered by an arching shawl. Amid the body's weathered verdigris, this face still shines with its original dark intensity.

The face haunts every visitor, for it is human but not clearly defined as to age, sex or mood. The surfaces are rounded and arching, the set of eyes and lips impassive. A face in repose, it looks toward something remote, beyond understanding. Adams thought he saw peace there, but later he sensed touches of defiance.

St. Gaudens drew the face from various models -- male and female, Sistine Chapel and a Japanese Buddha. He put some of his own secrets there, and perhaps those of his patron. The result is a work of perfect ambivalence, seen according to the eye and mood of its beholder.

Eleanor Roosevelt often visited the Adams Memorial, for she saw in its figure a woman who had attained self-mastery. That would have stunned Marian, who in her last days wrote to her sister, "If I had one single point of character or goodness I would stand on that and grow back to life."

As is so often true, her many points of character became evident too late, only after she was gone. All the more reason for remembering her today, a century later, in this season when the promise of light leads us through the darkest time of year.