Yet judging by the evidence of two new books about him, beneath the funereal exterior America's smartest (or perhaps luckiest) Federal Reserve chairman is one wild and crazy guy.

Greenspan's strange story is an oft-told one, but no less fascinating for it. After a hardscrabble childhood in New York's Jewish Washington Heights, he enrolled at Juilliard, only to drop out and become a professional clarinetist in a jazz band. He was a member of Rand's inner circle and a hard-nosed believer in her rationalist, free-market ideas, even during the left-leaning 1960s. And instead of toiling anonymously in some corporation, he acquired and expanded an economic consulting firm that made him a good deal of money even though his record as a forecaster was dismal. It took him more than 20 years to get his doctorate in economics, and he never did write a conventional thesis. He was also something of a ladies' man. Barbara Walters was among the many he dated.

In this credentialist age, it's unlikely that there will ever again be a Fed chief with a background as colorful as Alan Greenspan's. That's a shame because, as both books make abundantly clear, Greenspan's colorful past informs his decision-making at the Fed. Like any good jazz aficionado, he's comfortable about improvising and trusts his gut. And Greenspan's experience as a consultant and board member to large companies gives him a feel for business that many academic economists can't match.

Perhaps as a result, Greenspan has presided over the longest-running economic expansion in U.S. history, an age of low inflation, high employment and strong growth that seemed almost inconceivable during the 1970s.

To some extent, Greenspan has been lucky. An enormous confluence of factors has helped, including the microchip revolution and the rise of the Internet. But he's also been good.

According to Bob Woodward's disappointing Maestro, for instance, Greenspan several years ago had a sense that the data he was poring over was wrong - that low inflation, high employment and falling productivity taken together formed an economic oxymoron. But he couldn't prove it. Finally the Fed chief launched a massive research project to get to the bottom of this disparity and came to the conclusion that investment in new technology was causing a productivity boom, a boom that wasn't being measured by outdated economic yardsticks.

Of the two new Greenspan books, Woodward's is sure to make the bigger splash, in part because the press-shy Greenspan, according to the Washington Post (where Woodward is assistant managing editor), "appears to have cooperated extensively" with the author.

Unfortunately, the author's strong reportage is unadorned by even the most rudimentary literary skills. It's not even clear what the purpose of this book is. There is no particular thesis and little in the way of psychological insight. The effect is at times stupefying, as when Woodward details a series of long-ago quarter-point interest-rate changes.

Woodward's great strength lies in trading on his own legend to gain access other reporters might not get, here used to penetrate the depths of Federal Reserve machination. Not surprisingly, Greenspan emerges as a master political operator. The credibility of this portrait is simultaneously strengthened and subverted by Greenspan's apparent cooperation, which gives Woodward the chance to talk about what the Fed chief thought at various times, but which also makes Woodward himself - and the reader by extension - the subject of Greenspan's considerable and subtle manipulative skills.

The picture is more or less credible, though, because it isn't always pretty, and it matches the one painted by Justin Martin's book.

A former staff writer at Fortune, Martin tells us that as chairman of the Council of Economic Advisors under Gerald Ford, Greenspan turned the three-member panel into a one-man band, unapologetically hogging presidential face-time and important work for himself. Greenspan would do the same later as Fed chief, a position he has held since 1987. Examples abound. Federal Reserve interest-rate decisions, for instance, are largely the province of the Federal Open Market Committee, a panel Greenspan has managed entirely to co-opt, driving out influential potential dissidents such as Alan Blinder, an economist who argued that higher growth was possible without additional inflation.

Martin's book is more of a conventional biography than Woodward's and works well as such, as it packs a good account of its subject's life as well as an admirably clear explanation of the Fed and its history into just 233 pages of modest prose. (Woodward's is about the same length, but feels longer.)

Martin too does a good job revealing Greenspan's political skills, demonstrating, for example, how his subject's cards-close-to-the-vest approach stood him in good stead during his well-known involvement with Ayn Rand's Collectivist circle in New York. Greenspan got involved with this odd group through his first wife, Joan Mitchell, with whom he remained close even after their 10-month marriage ended.

For most of the young Collectivists, Martin shows, Rand was something of a Svengali, a role that stood in ironic contrast to the group's rigorously individualistic principles. But while some members of the group became emotionally entangled with Rand, Greenspan kept his own counsel, made a life for himself outside the incestuous Collective, and managed to stay on everyone's good side when the whole thing collapsed in bitter recrimination.

It's no surprise then that Bill Clinton and Alan Greenspan have gotten along. Both are brilliant intellectually as well as politically, and both have the ability to tell everyone what they want to hear. Greenspan's talent for double-talk is renowned; Martin shows that this is a strong Fed tradition, although no one has ever come close to the current chairman's heroic murkiness. Greenspan even used to practice his double-talk in front of his staff at the Council of Economic Advisors. Woodward reports that obscurity has become such a habit for Greenspan that he had to ask TV correspondent Andrea Mitchell to marry him twice because the first time he either didn't make himself clear or it didn't register.

Both writers ultimately support the conventional wisdom that Greenspan has had an extraordinary run as Fed chairman. Shortly after taking office, he showed his mettle by keeping a cool head and pumping liquidity into the system following the crash of '87. He subsequently guided the U.S. economy - and, to a large extent, the world economy - through a serious banking crisis, the Asian and Russian meltdowns and the collapse of Long Term Capital Management.

Woodward - echoing his previous book about the Clinton administration, The Choice - makes plain that Greenspan was also instrumental in persuading Clinton to push a major deficit-reduction package through Congress, arguing that without fiscal restraint the economy would never enjoy the low interest-rate environment so conducive to long-term growth.

Along the way, he had his hand on the money-supply spigot, which he operated with uncanny sensitivity. One strength of Woodward's book is that it shows just how difficult it is, when most of your data is complex, conflicting and reflective of events already in the past, to take intelligent action on the money supply. Somehow, Greenspan has managed it.

And while Greenspan was all wrong about "irrational exuberance" in the stock market, his comments were taken out of context in a way that made him seem more wrong than he was (remember, Greenspan never really says anything if he can help it). It's ironic that the phrase struck such a chord because, beneath his dour mien, Greenspan's own life would seem to exemplify a kind of rational exuberance. He appears to have a cautiously optimistic confidence not just in his own considerable powers but also in his own fate - which is why he became not an accountant but a jazz musician, then a wary acolyte of the guru of individualism, and then, finally, a guy with a sign in his office saying, "The buck starts here."

In some ways Greenspan's monetary power is like Tinkerbell's life: dependent on the expressed faith of others. Which is to say, not so very different from money itself. The question now is how long the chief can keep that belief afloat. These two brief books, each applauding in its own way, should supply some helpful levitation.