The monuments of the monstrously rich are strewn across urban American. In Washington, the National Gallery testifies to the financial potency of the Mellons. In my own New York, the Frick Collection embodies its dour donor's rare concern for the public welfare. For better or worse, the architecture of Manhattan has been shaped by three generations of Rockefellers -- the United Nations, Rockefeller Center, the Museum of Modern Art, Riverside Church, the Cloisters, Lincoln Center and, most recently, the dreadful twin towers of the World Trade Center.

The elder Morgan, the subject of this brisk portrait, flourished between the Civil War and World War I. His contribution was the magnificent Morgan Library on Madison Avenue, a repository of rare books, manuscripts, engravings and incunabula. Morgan naturally collected money first, but his tastes increasingly ran, particularly after his masterful father, Junius, died, to the acquisition of yachts, beautiful mistresses and art objects.

Relying upon standard sources, Sinclair tells a familiar story. Between the 1830s, when Andrew Jackson eliminated the Second Bank of the United States, and 1913, when the Federal Reserve System came into being, this country lurched from financial crisis to financial crisis without help from any counterpart to the Bank of England. That bank, like other central banks, acts as lender of last resort, guarantor to investors and depositors that if worse comes to worst their funds will be protected by an institutional Maecenas equipped with reassuringly deep pockets.

It was precisely the absence of such recourse that allowed Wall Street investment bankers to dominate national policy and bring to heel reluctant presidents. Abraham Lincoln had to appeal to the bankers to finance the Civil War. Theodore Roosevelt was compelled to do business with Morgan in order to slow the dangerous drain of gold to foreigners. Repeatedly Morgan organized rescue parties for faltering banks and trust companies, a mission these days quietly executed by the Federal Reserve and the Federal Deposit Insurance Corp.

This activity amounts to half the case for Morgan. The other half is his substitution of industrial rationality for the chaotic, destructive competition that marred the 19th-century record of railroads, steel, oil refining and other industries. As the case runs, much as the elder Rockefeller reorganized oil refining, Morgan brought to their senses railroad and steel magnates.

Neither apology is especially persuasive. As Thorstein Veblen devastatingly suggested and the Pujo Commission demonstrated, the Wall Street movers and shakers more frequently than not generated the crises from whose effect Morgan and his allies subsequently saved the country, invariably with lavish profits to themselves. Morgan's most spectacular creation, U.S. Steel, "did little," in the judgement of Alfred Chandler in his magisterial "The Visible Hand," "to coordinate, plan, and evaluate for the activities of the subsidiaries."

Possibly to the relief of readers bored by the details of ancient business maneuvers, Sinclair is far more interesting in his account of Morgan as a personality than as a financial titan. Morgan must have been a fascinating human specimen. A devout Episcopalian, he faithfully attended the triennial conclaves of his church and, even more remarkably, listened to the speeches. Yet this devout Christian and celebrant of family life numbered among his female trophies the celebrated actress Maxine Elliott. During the Civil War, the devoted patriot played a questionable role in the Hall Carbine affair and like other affluent, healthy males hired a substitute to fight in his stead.

Sinclair makes a temperate claim for Morgan's increasing expertise in the selection of art objects, but the financier always had the good sense to depend upon the Duveen brothers' counsel, and he preferred to buy entire collections rather than single items, the choice of a plutocrat rather than a serious collector.

Morgan's preeminence among the obscenely rich derived in part from the head start his father gave him among rivals who started a generation later, and, for the rest, from the fear and awe he struck in his contemporaries. Even partners scuttled like office boys into the imperial presence. His silences were celebrated. In a secluded room of his library, he would sit hour after hour, playing solitaire, and waiting for wrangling financiers to present him with a proposition he could endorse. It attests to the man as a force of nature that almost invariably the proposition was forthcoming.

The competent writer of popular biography, Sinclair does his professional best to turn this plutocrat of plutocrats into a sympathetic charter. That he fails attests perhaps to his own shortage of enthusiasm and certainly to his subject's recalcitrance to rehabilitation.