There are a few personal qualities that we have come to expect of all our politicians. We take it for granted that they will be reasonably likeable; that they will be polite to constituents and careful not to talk over their heads; that they will be generally optimistic about the future, if not the present; and that they will tell us that public problems are, in the end, solvable.

It's possible to cheat on one of these basics and still win elections. We can all think of a few who have done it. But what kind of a career can a politician have if he disdains every one of them? Basically, the answer is not much of a career at all. Unless, that is, he is Jerry Brown. This politician broke virtually every norm of public social comity, won four elections as governor of California, and left office last year with an exemplary reputation not only in his state but all over the world.

How did he do that? And are there lessons his unlikely career might offer politicians of the future? Perhaps not. "I can't see anyone patterning themselves on his persona," the political scientist Thad Kousser remarked a couple of years ago. Kousser described that persona succinctly. "Be grouchy and supercheap, quote obscure philosophers, avoid social media, and never make a public presentation without a doomsday-predicting graph." It's not much of a formula for attracting public adulation, is it?

Perhaps the best move is to accept that Brown was unique and move on to another subject. But in the last couple of years, two very good books have taken the measure of Brown's nearly 50-year career in California politics and sought to reach some conclusions about what sort of man this actually was. One is 2018's The Browns of California, by the journalist and scholar Miriam Pawel. The other, published this spring, is Man of Tomorrow, by Jim Newton, a former Los Angeles Times editor and columnist.

One fact that emerges crystal-clear from both books is that Brown was (and is) a man of paradox. I have always been suspicious of arguments based on paradox. They usually tell you that someone or something is both A and B, but that doesn't really answer any hard questions. In Jerry Brown's case, however, the paradoxes stand out so glaringly that they may be where you have to begin.

Let's start with this one: Brown's half-century in politics, from his election to a Los Angeles community college board in 1969 at age 31 to his final retirement from the governorship in 2019, was a baffling combination of brazen ambition and humble self-abnegation.

By one indisputable standard, he was a compulsive and somewhat irresponsible campaigner. Almost as soon he took office as governor in 1975, having won the office in large part because he was the son of former Gov. Pat Brown, he started running for president. He did pretty well, too. He won five primaries before losing the Democratic nomination in 1976 to Jimmy Carter. Despite a credible record of accomplishment in his first year as governor, one that included a landmark law providing legal protection for farmworkers, it was never clear what he was running for president on, other than being a fresh face and claiming that the other candidates weren't exciting enough.

He ran again in 1980, shortly after his re-election as governor, dropping out when he saw that the Democratic primaries were a contest between Carter and Edward M. Kennedy. He tried once more in 1992, this time running a cranky and mean-spirited effort that accused everyone else in the Democratic field of campaign-finance corruption. It's hard to see that record as anything but an extended exercise in egotism.

But all along the way, he was making impassioned confessions of personal humility. There is nothing unusual in a politician proclaiming his modesty, but Brown went quite a bit further. "You need someone who's been trained in the arts of self-abnegation and mortification," he declared early in this career. "You must die to yourself." Brown attributed this conviction to his three years in a Jesuit seminary in the 1950s. The California electorate bought it and, in 2010, returned him to the governor's mansion for a third time.

HUMBLE AND EGOTISTICAL, BRASH AND DIFFIDENT. Those are all good ways of describing Jerry Brown, at least in his first few political decades. To say he didn't suffer fools is an understatement. Even at the height of his early success, political writers came to California and marveled at the fact that more than 85 percent of the California electorate approved of him. "He is the most interesting politician in the United States," The New York Times proclaimed in 1976, "and at the moment he is one of the most popular," despite the fact that "he is not a particularly likeable young man" and asks "hostile and irreverent questions."

There is also the paradox that Brown was, his constant campaigns notwithstanding, an introvert in politics. That's not unknown; Richard M. Nixon certainly fit that description. But Nixon turned on the bonhomie when he had to; Brown almost never did. And he admitted it. He confessed his distaste for the public as early as his seminary years. "I don't quite enjoy the crowds and the handshaking," he said when he first became governor. "I'm not ready to sentence myself to a life in politics." His chief of staff once admitted that Brown "just doesn't have what people typically think of as personal relationships with people." But a long life in politics is what he conducted, and seemed unable to escape. A pretty good paradox, if you ask me.

There's no real reason to doubt Jerry Brown's sincerity as a moralist. He was a consistent advocate of personal responsibility, from his first term as governor, when he opposed a helmet requirement for motorcyclists on the grounds that they must practice correct behavior on their own. Around the same time, he was asked to define his objectives in politics. His answer was: "Reduce the sum of human misery, I guess. Help people expand their lives a little bit, give them an awareness of their own potential." All of this paints a portrait of a man with strong moral convictions struggling to implant them in public life.

But then there is the Brown who could be disturbingly, sometimes shockingly, pragmatic. Exhibit A is his awkward reversal on Proposition 13, the massive and ultimately crippling property-tax cut that California's voters approved in June of 1978. Adamantly opposed to it at first, Brown ended up supporting it in his re-election campaign that fall, describing himself as a "born-again tax cutter." There is also the Brown who accepted the position of chairman and chief fund-raiser of the California Democratic Party in 1989, then quit that job to launch a presidential campaign in which he denounced the system he had just been part of. Defensible, perhaps: There is such a thing as genuine remorse in politics, even instant remorse. But in this case it is part of a paradoxical public life.

Finally, there is the uneasy balance between Brown the dreamy visionary, the "Governor Moonbeam" who based a presidential campaign on a promise to explore the universe, and the sober realist who spent decades proclaiming that no administration could solve many of the most perplexing public problems close to home. "I view with some skepticism," he announced in his first gubernatorial campaign, "the ability of government to make people happy." It's common to hear politicians proclaiming the impotence of government — Republicans do it all the time. But Brown had something else in mind: He didn't just say that government couldn't cure their ills; he said nothing could. "There are limits to the planet," Brown declared in his first term as governor. "There are many things that cannot be solved."

THE AUTHORS PAWEL AND NEWTON ascribe the emergence of a truly new and different Jerry Brown to his political comeback in Oakland, across the bay from San Francisco, where he was elected mayor in 1998. Suddenly he began paying less attention to sweeping philosophical controversies and focusing more on the mundane challenges of modern urban life. "When I was governor," Brown said, "it was 'labor' or 'the environment.' In Oakland it was somebody wanting to build a house on a lake."

Whether or not the Jerry Brown who returned to the governorship in 2011 was a genuinely reborn public figure, he was a politician unlike the one who had taken over in Sacramento 36 years earlier. Once he had been a disrupter, Pawel explains. Now he was a mender. He was also a deal-maker in ways he had never been before. He lobbied hard and successfully for prison reforms and action on climate change. He held the line on questionable spending programs his fellow Democrats wanted to implement. But the signature accomplishment of Brown 2.0, indeed of his entire political career, was Proposition 30, an increase in income and sales taxes that took the state from the brink of fiscal insolvency to a condition of stable economic health.

When he left Sacramento for his ranch in Colusa County, at the start of his ninth decade of life, Jerry Brown was the most popular California governor in modern history. And he deserved to be. Flaws and all.

But in the end, what are we to make of this wildly improbable public life? Does it offer any lessons at all to the aspiring politician? I can think of one: Follow your own instincts to the extent you can at any given moment, accepting the inconsistencies that such stubborn behavior generates over a long career. Ignore the paradoxes; you will never resolve them. To quote two of Brown's Jesuit mantras: "Do what you are doing." "Live in the inquiry."

That's the best I can come up with, given the fact that Brown himself has never quite understood why he did the things he did. "As much as I dislike politics," he said toward the end of his political career, "I have devoted my life to it — out of some form of enlightened masochism or some other deep motive that I have not yet been able to plumb." Students of government can keep trying, but they are unlikely to plumb it either.