In The Zealot and the Emancipator, historian H.W. Brands reflects on two 19th century leaders who fought the institution of slavery in different ways: one radical and the other reformist.

H.W. Brands chairs the history department at the University of Texas at Austin. He's written more than a dozen biographies and works of history, two of which were finalists for the Pulitzer Prize. He joins me from his home in Austin to talk about his new book, "The Zealot And The Emancipator: John Brown, Abraham Lincoln, And The Struggle For American Freedom."

Well, H.W. Brands, welcome to FRESH AIR. These are two historical figures whose lives, you know, have been pretty well chronicled - Lincoln, especially. Why did you want to consider them again and together?

H W BRANDS: Partly because they address a timeless question, especially in a democracy - what does a good person do when the government that that person lives under is engaged in something evil - in a great evil, in fact? And the evil that John Brown and Abraham Lincoln agreed on was slavery. But they differ dramatically on the most effective, the most appropriate way of dealing with that. This is a question that comes up in every generation. It could be the Vietnam War. It could be the current crisis over race relations and a reckoning with race. And I thought it was worth looking at in the context of the 19th century and the overriding issue then of slavery.

DAVIES: So let's talk about John Brown first. He is best known for the raid on Harpers Ferry, Va., which is, by the way, now in West Virginia. That was the event that ended his life. But he was a pretty fascinating character long before that. Tell us just a bit about his life and what distinguished him, particularly on the subject of race relations.

BRANDS: John Brown was born in 1800, and he spent the first 35 years of his life trying to figure out what to do with himself. He married twice. His first wife died. He had 20 children. But he never could quite make a success at anything. He tried his hand at various occupations. He finally found his calling, though, when the abolitionist movement really took hold in the United States in the 1830s.

He had always been opposed to slavery. He recalled a moment when one of his playmates, a Black boy, had, for no good reason, just been beaten about the head with a shovel by his master. And young John Brown thought this was wrong, but he couldn't quite figure out what to do about it. But when Elijah Lovejoy, an abolitionist editor, was killed - was murdered by a mob in 1837, John Brown decided that this was the cause of his life. This was what he had been preparing for. And he stood up in his church in Hudson, Ohio, and announced that he would forever after wage war against slavery.