IN THE FALL OF 1879, a brilliant young widow named Madeleine Lee moved from New York to Washington. Her twin objects: to observe the workings of the United States government, and to meet great men. Or at least to see if the District has any to meet.

Mrs. Lee has found greatness to be in very short supply in New York. The New York men she knows all seem to be stockholders. Millionaires, many of them, but lacking in ideas. She is rich herself (her $30,000 a year would easily equal $300,000 a year now); and mere wealth does not impress her.

When she visits Boston, it's no better. There are scholars and artists in society there, to be sure, well-bred and prosperous; but they mainly strike her as dilettantes. "You are just like the rest of us," she tells a Boston friend. "You grow six inches high, and then you stop. Why will not somebody grow to be a tree, and cast a shadow?" Some months later it occurs to her that a U.S. senator or the president might cast a shadow. Hence her move.

So begins the best political novel yet written in America, Henry Adams' Democracy . The author had extraordinary qualifications for writing it. His own family had been casting shadows for three generations. His great-grandfather, while serving as president of the United States, was the one who supervised the transfer of our government to Washington, in 1800. His grandfather had been both president and a congressman. His father had been both amabassador to England and a congressman. (Well, actually minister to England -- in those days we were a more modest nation.) He himself was a writer, not a politician, but he knew Washington inside out.

Democracy is a comedy, and an extremely funny one. My favorite scene is the one where Lord Skye, the British minister, is giving a gala ball in honor of the grand duke and duchess of Saxe-Baden-Hombourg. (He has to, because the grand duchess was born an English princess.)

Because he knows that everybody who is anybody will want to come to the ball, and the British embassy though large is finite, Lord Skye cleverly waits until Congress has recessed. Then he issues invitations with a lavish hand. Among others, he invites:

". . . all the senators, all the representatives in Congress, all the governors of States with their staffs, if they had any, all eminent citizens and their families throughout the Union and Canada, and finally every private individual, from the North Pole to the Isthmus of Panama, who had ever shown him a cilivity, or was able to control interest enough to ask for a card. The result was that Baltimore promised to come in a body, and Philadelphia was equally well-disposed; New York provided several scores of guests, and Boston sent the governor and a delegation; even the well-known millionaire who represented California in the United States Senate was irritated because, his invitation having been timed to arrive just one day too late, he was prevented from bringing his family across the continent with a choice party in a director's car."

Many things happen at that ball, including a proposal to Mrs. Lee, and a glorious success on the dance floor for her 24-year-old sister Sybil, the mere description of whose dress is one of the most charming pieces of writing I know. The main action, though, is right out of Lewis Carroll.

Naturally the president and his wife are present. As it happens, the president is a former Indiana farmer (and state governor) known to his friends as Old Granite and to his enemies as Old Granny. His wife is both strong-minded and very puritanical. She and the grand duchess (equally strong-minded) take an instant dislike to each other -- in fact, declare war. Result: All evening the two women are seated on identical sofas, on opposite sides of the ballroom, the royal insignia above one, and the American eagle above the other, two angry queens on thrones. Each wishes to prevent all the more important guests from talking to the other, and so each is gathering them around her sofa, as one might take chess pieces. It is a splendid piece of writing.

But Democracy cuts deeper than social comedy. It is also a serious look at American government as Madeleine gradually comes to understand it. And here is operates on no less than three levels.

When Madeleine arrives in Washington, she very quickly meets an authentic great man. His name is Silas P. Ratcliffe, he is a senator from Illinios, and he is the leading Republican in the country, more powerful even than Old Granny. Both literally and figuratively, he is very much more than six inches tall. In fact, he's known as the Prairie Giant of Peonia. He is 50 years old, and a widower.

Partly through her beauty and intelligence, and partly by going to hear him in the Senate and telling him afterwards that he speaks as well as Daniel Webster (he "rose to this gaudy fly like a huge, two-hundred-pound salmon"), Madeleine soon has Senator Ratcliffe in love with her. And not just in love, but eagerly sharing the dilemmas of government. For a time Madeleine is deeply impressed.

Meanwhile, another, less obviously great man has also fallen in love with her: an incorruptible Virginia lawyer named Carrington, who is a kind of collateral descendant of George Washington. Carrington recognizes Senator Ratcliffe's greatness, but knows that it is the greatness of mere ambition. He also knows what is otherwise a well-kept secret, that Ratcliffe once took a $100,000 bribe from a steamship company. (A handsome sum. U.S. senators were getting paid $5,000 a year at the time.) He is determined to prevent the marriage. So, for quite different reasons, is old Baron Jacobi, the Bulgarian minister. The central plot of the book concerns this struggle over Madeleine Lee.

On the top level, Adams was writing a roman a clef . Senator Ratcliffe was modeled on James G. Blaine, a great (and corrupt) Republican leader. Similarly, Old Granny is a wickedly funny amalgam of presidents U.S. Grant and Rutherford B. Hayes. Even Baron Jacobi is drawn from that remarkable Turkish diplomat and man-about-19th-century-Washington, Aristarchi Bey. Blaine, incidentally, recognized himself with no trouble when the book was published, and was furious.

That level is minor. More important is sthe next level, on which Adams judges the men -- and women -- one meets in public life. Every character in the book gets classified either as a boor or as a civilized person. The boors, led by Senator Ratcliffe, include the president, the grand duchess, a large number of other senators, and Mrs. Baker, the pretty blonde lobbyist. The civilized people, led by Carrington, include Mr. C. C. French, the reform congressman from Connecticut, Mr. Gore of Massachusetts, Lord Skye, and, of course, Madeleine herself. On this level Democracy is a happy book with a happy ending. Carrington does thwart Senator Ratcliffe, and there is even a scene, which Adams msut have loved writing, where the old roue Jacobi cracks Ratcliffe over the head with his cane. Culture and breeding triumph.

But there is also a third and much gloomier level. Here Adams is judging the age itself. Without ever being obvious about it, he makes Carrington stand for the early days of the Republic, for the ideals of George Washington, and Ratcliffe stand for the America of party politics. On this level Ratcliffe wins hands down. Carrington may prevent him from marrying Madeleine Lee, but he cannot keep him from running the country. He cannot even hope that a change of party, or such piddling reforms as Mr. C. C. French dreams of, would make the faintest difference. At the heart of the book is a radical despair.

That in no way spoils the comedy, however. (There is lots more I haven't even mentioned, such as the story of Miss Victoria Dare, the stammering b-b-bad girl of Washington society, and her outrageous flirtation with Lord Dunbeg.) It just gives the book a kind of resonance.

And perhaps Adams' despair of American politics was not total, after all. Five years after the book came out, he made over the copyright to the National Civil Service Reform League, and for almost half a century, until long after his death, the royalties went into the effort to make democracy work. Casting a shadow, that's called.