If history, as Edward Gibbon said, is “little more than the register of the crimes, follies, and misfortunes of mankind,” it makes sense that the greatest criminals tend to receive the most attention from historians. Napoleon, a tyrant who was responsible for millions of deaths, is the most biographized figure in modern history, and it seems that new biographies of Stalin and Hitler crowd the bookstores every year. It is pleasant to be reminded, then, that good men can also make history from time to time — that humanity is not too fascinated by its destroyers to pay tribute to its benefactors.

“John Stuart Mill: Victorian Firebrand” (Overlook, 616 pages, $40), an accessible and admiring new biography by Richard Reeves, is such a tribute. Mr. Reeves — a British journalist, not the American biographer of presidents Kennedy, Nixon, and Reagan — works hard in this book to humanize Mill, to rescue him from his deadening fame as “a bone-dry, formal, humourless Victorian.” At times, perhaps a little too hard: On the very first page, Mr. Reeves strains to shock the reader with a description of the dead baby Mill once found in St. James’s Park, followed immediately by the detailed contraceptive instructions that this discovery spurred Mill to distribute to the London poor. (“A piece of soft sponge is tied by a bobbin or penny ribbon, and inserted just before the sexual intercourse takes place,” and so on.)

Throughout the book, Mr. Reeves seizes every opportunity to “sex up” Mill’s image, as the British say — whether the subject is sex itself, or the fierce political battles in which Mill participated, or even something as benign as his aesthetic appreciation of Italian churches. Anything to convince the reader that Mill was not what Thomas Carlyle called him after reading Mill’s “Autobiography”: a “logic-chopping engine,” “a thing of mechanized iron.”

The characterization was unfair but understandable, since Mill was, in fact, almost literally engineered to become a philosophic reformer. His father, James Mill, a close friend of Jeremy Bentham, believed that a perfect education would inevitably produce a perfect human being, and he tested his theories on his oldest son. John Stuart Mill’s education has become legendary: He had no toys or friends, but he could read Plato in Greek by the age of 7, and by 12 he was attending chemistry lectures at the Royal Military College. This regimen, which appalled everyone who heard about it — “If anything could make intellectual culture odious and terrible, it is the example of that overstrained infant,” wrote one friend — did manage to make Mill a genius. It also cost him a nervous breakdown in his 20s, and left him susceptible to depression throughout his life.

Nothing is more impressive in Mill’s story than the way he overcame this potentially ruinous childhood. Thanks in large part to his love for Harriet Taylor — a married woman who was his close companion for decades, and then his wife — Mill turned himself into the rarest kind of reformer, one who is as genuinely humane as he is effective. If Mill was a “firebrand,” as Mr. Reeves’s subtitle suggests with a flourish, he was not the kind who wanted to burn down factories, or churches, or Parliament.

There were such men in England and Europe during Mill’s lifetime (1806-73), and at moments he could even sympathize with them. He gloried in the French revolution of 1848 — “There never was a time when so great a drama was being played out in one generation,” he wrote — and in his lifelong battle with British prejudice and complacency, he sometimes yearned for a similar upheaval at home. “England has never had any general break-up of old associations,” he grumbled, “and hence the extreme difficulty of getting any ideas into its stupid head.”

But “in truth,” Mr. Reeves points out, “Mill was anti-revolutionary at home.” His fire was not for burning, but for shedding light, and his society was unusually willing to have its dark corners illuminated. Far from suffering the usual fate of a prophet in his own country, Mill became a revered figure in Victorian England. The magazine he edited, the London and Westminster Review, was a must-read for radicals and intellectuals; his dense philosophical treatises, “A System of Logic” and “Principles of Political Economy,” were best sellers; he was even elected to a term in Parliament, though he didn’t accomplish much there.

Most telling of all, Mill spent most of his adult life working for that pillar of the establishment, the East India Company, which gave him a princely salary and frequent vacations to support his intellectual work. Socrates, when asked at his trial what punishment he thought he deserved, ironically suggested that the Athenians give him free room and board for the rest of his life. He ended up with the hemlock, but Mill actually did enjoy something like Socrates’s ideal: a comfortable position, including a summer house in Provence, from which to chastise the society that sheltered him.

In its treatment of Mill, Victorian England approached the ideal that he set forth in “On Liberty,” his most influential book, and the one discussed most penetratingly by Mr. Reeves. The first and most important kind of freedom, Mill argued, was intellectual — the freedom to argue and criticize, to hold unpopular opinions without being punished or silenced. The basis of his argument was not simply that all men have the right to free speech — though he did certainly believe this — but, more interestingly, that society injures itself when it curtails the free exchange of ideas. “The peculiar evil of silencing the expression of an opinion,” Mill writes, “is, that it is robbing the human race; posterity as well as the existing generation; those who dissent from the opinion, still more than those who hold it. If the opinion is right, they are deprived of the opportunity of exchanging error for truth: if wrong, they lose, what is almost as great a benefit, the clearer perception and livelier impression of truth, produced by its collision with error.”

What breathes in this passage, as in all of Mill’s work, is a profound trust in human nature, and still more in human potential. Yet Mill was far from believing that all men are good. In fact, to the consternation of democrats then and since, he did not believe in universal suffrage, on the principle that the English working classes of his own day were too ignorant and degraded to be trusted with political power. (As Mr. Reeves shows, he was sobered by the example of France, where the universal suffrage won in 1848 was used to crown Napoleon III emperor a few years later.)

Mill did believe, however, that every man and woman had the capacity to govern his or her own life — to think and judge independently of authority and tradition. More, he believed that this freedom constituted the nobility of human nature, and the school of all the virtues. Freedom was not a merely negative state, an affair of being left alone; it was a positive estate, which human beings have to claim for themselves by thinking and working. Mill is never more inspiring than when he describes the elation of this freedom:

Let any man call to mind what he himself felt on emerging from boyhood — from the tutelage and control of even loved and affectionate elders — and entering upon the responsibilities of manhood. Was it not like the physical effect of taking off a heavy weight, or releasing him from obstructive, even if not otherwise painful, bonds? Did he not feel twice as much alive, twice as much a human being, as before?

As a philosophical tradition (as distinguished from its current use as a partisan political term), liberalism has often been derided as bloodless and unemotional. To its enemies, liberalism means a passionless neutrality, a focus on process rather than meaningful goals, and an impoverished view of human nature as driven strictly by fear and greed. Mill’s life and work are most important today as a refutation of these slanders, a proof that the liberal tradition — which is the American tradition, going back to the Founding Fathers — rests on a rich and noble understanding of human possibility. Mill, who was himself raised in a benevolent but absolute paternal tyranny, knew the delights and burdens of freedom as intimately as any writer ever has. That is why he insisted that every human being deserved to experience freedom, even when the conventional wisdom of his day held that women, or workers, or Africans, were simply incapable of it.

As Mr. Reeves shows, Mill’s specific political views do not map neatly onto today’s categories of left and right. He was against state control of education, and proposed something very like a voucher system; he believed in a flat tax, on the principle that progressive taxation punished the hardest-working, and he feared for the fate of the individual under socialism. At the same time, he saw inherited wealth as a force for injustice, and advocated confiscatory inheritance taxes; he believed that the state should own all land, to prevent a narrow aristocracy from engrossing the gifts of nature, and he was a sharp critic of organized religion. What united all these opinions, as Mr. Reeves skillfully shows, was a constant dedication to liberty as he understood it: “the consciousness of working out [our] own destiny under [our] own moral responsibility.”

akirsch@nysun.com