American politics is replete with practitioners who preach honest politics while failing to practice it.

Thomas Brackett Reed of Maine, late-19th-century Speaker and the subject of James Grant’s winning new biography, “Mr. Speaker! The Life and Times of Thomas B. Reed,” was the opposite.

He was a man who practiced honest politics but never preached it. “Pure in his political conduct,” Grant writes, “he had no interest in instructing the impure.” And in the end, he walked away from power rather than practice a style of politics he found personally distasteful and considered dangerous to American ideals.

But before that, he was, in the words of the book’s second subtitle, “the man who broke the filibuster.”

In modern times, the filibuster is an exclusively Senate phenomenon. But in the 19th century, the House was in some ways even more unruly than the Senate. Those seeking to block action had to do nothing more than refuse to acknowledge their presence, thereby depriving the body of a quorum and making it impossible to conduct any legislative business.

Grant does a splendid job of describing why it was necessary for Reed to put an end to this practice when he became Speaker. He offers multiple examples of dilatory chicanery that make today’s delaying tactics look like a junior-high version of the four-corner offense.

Reed, a serious legislator who often operated in a comic vein — more than a century after his death he is still considered one of the wittiest people ever to lead the House — had seen enough of such nonsense. So he devised a system that ensured any warm bodies on the House floor were counted as present, even if they refused to answer a quorum call. That ended the filibuster and earned the Speaker the title of Czar Reed, a label he didn’t seem to mind at all.

Reed did not earn the sort of lasting reputation that some other Speakers have. He is not revered like Henry Clay, and he does not have a House office building named after him like Joseph Cannon, Nicholas Longworth or Sam Rayburn. If he is remembered at all, it is for some of his “eviscerating wit.” Sarcasm was his “native language,” Grant observes, a condition that undoubtedly played a role in keeping Reed from being more of a party favorite than he was and also might have had a part in keeping him out of the White House.

Grant is a financial writer and his proclivity for monetary policy shines through in “Mr. Speaker!” just as it did in his other political biography, “John Adams: Party of One.” “Mr. Speaker!” is a useful primer on Gilded Age monetary policy — so much so that in some parts of the book, Reed disappears for pages at a time while Grant expounds on the gold standard, silver monetization and tariffs.

It’s not a tight narrative, but episodic, at least as much “times” as “life.”

But that’s OK because Reed lived in interesting times. He came to national power at the end of Reconstruction, sat on the committee that investigated the corrupt 1876 presidential election and often took policy positions that were wildly out of step with his contemporaries. He opposed capital punishment and federal subsidies for railroads, supported women’s suffrage and had a dim view of organized religion.

Despite all that, through the power of his intellect and his mastery of parliamentary maneuvering, Reed rose to the speakership and was considered a serious contender for president in 1896.

In measuring his own chances at the Republican convention that year, Reed quipped that “they could do worse — and probably will.” The nomination went to William McKinley.

McKinley’s election set the stage for Reed’s ultimate political demise. The turn toward American empire the country took near the end of the century was opposed by Reed, but even as Speaker, he had few tools to impose his will. The charge toward war with Spain and the annexation of foreign lands that resulted cost Reed two of his closest political friendships — with Theodore Roosevelt and Massachusetts Sen. Henry Cabot Lodge.

Grant’s telling of the demise of the Reed-Roosevelt-Lodge alliance is not nearly as lachrymose as the version in Evan Thomas’ “The War Lovers,” but it still conveys the sense of loss felt on all sides. Lodge wrote in his diary that Reed had “set himself against the evolution of the country & the forces of the time.” It was an assessment Reed could hardly argue with.

“It was time to leave,” Grant writes, “and he left.”

As a freshman lawmaker in 1878, Reed delivered a speech on the occasion of Maine’s selection of Gen. William King to represent the state in Statuary Hall. King had been dead for about a quarter-century at the time.

“We all know too sadly well that oblivion begins to devour the mightiest when dead,” Reed said, “and has in all ages been so greedy as to overtake some men yet living.”

After his death, oblivion overtook Reed quite quickly. Grant has helped restore him to his rightful place among the giants of the House.