When I asked Karl Rove this week to summarize his approach to politics, he quoted from memory a 167-year-old letter by Abraham Lincoln to his Whig campaign committee: "Keep a constant watch on the doubtful voters, and from time to time have them talked to by those in whom they have the most confidence."

Rove's innovation was to bring this peer-to-peer politics to a continental scale. Microtargeting and intensive turnout efforts helped win West Virginia by 6 points in 2000 (Bob Dole had lost the state by 15 points in 1996) and improbably elected a Republican challenger in a time of Democratic prosperity. "In election after election," Rove observes, "we were applying Lincoln's letter."

It is a typical Rove response -- a sophisticated electoral strategy wrapped in an obscure historical reference. His background in direct mail, along with the experience he gained while converting Lyndon Johnson's Texas into a Republican stronghold, has given him a comprehensive understanding of the technologies and trends of politics.

But in several years as a colleague, I found Rove to be the most unusual political operative I have ever known; so exceptional he doesn't belong in the category. His most passionate, obsessive love -- after his wife -- is American history. He visits its shrines and collects its scraps -- carefully archived pictures of President William McKinley's funeral, original ballots from the 1860 election. And from American history Rove knows: Events are not moved primarily by techniques; they are moved by ideas.

Rove's main influence on the Republican Party has not been a series of tactical innovations but a series of strategic arguments. In this way, Rove is the opposite of a cynical political operator. He is not only a partisan for George W. Bush but the most serious, tireless advocate of Bushism.

First, Rove argues that Republicans win as activist reformers, in the tradition of Lincoln, McKinley and Theodore Roosevelt. "We were founded as a reformist party," he said in our conversation this week, "not to be against something, but to help the little guy get ahead." The models he cites are 401(k)s and the mortgage interest deduction -- government policies that encouraged individual wealth and ownership. Then Rove spent several minutes describing, with wonkish delight, the momentum and virtues of health savings accounts, a Bush-era innovation allowing individuals to save tax-free for routine medical expenses.

The activist use of government to help individuals get ahead may not sound controversial. Among Republicans, it is. In the 1996 presidential election, Dole's domestic message focused on the limits and flaws of the federal government -- he talked endlessly of the 10th Amendment to the Constitution, which constrains federal power in favor of the states. In 2000, Bush's main domestic proposal concerned the use of federal power to catalyze state education reform -- a head-snapping contrast.

Second, Rove has argued that tending to your political base and reaching beyond it are not incompatible. He talks of raising "bold colors" on conservative issues such as tax cuts, the protection of unborn life and the appointment of originalist judges. At the same time, he has advocated policy innovations to appeal to new voters. "How can it be all about the base," asks former Republican National Committee chairman Ken Mehlman, "when Karl is also the biggest supporter of prescription drugs for seniors and immigration reform that allows for earned legalization?" From 2000 to 2004, this approach excited conservative enthusiasm; boosted President Bush's support among Hispanics, Asian Americans, Catholics and women; and increased his popular vote total in his reelection bid by 23 percent.

Third, Rove has argued that the Republican Party will need to appeal to minorities or gradually decline. "We can't be the party of America," he says, "and get 13 percent of the African American vote." And given demographic trends, it is hard to imagine that Republicans will remain a national party if they alienate Latinos. Looking back at his career, Rove is particularly proud that "when we ran in Texas in 1998, among the statewide Republican ticket, a minority of the candidates were white men." Rove has shown a consistent commitment to inclusion, as both a moral good and a political necessity.

It is sometimes alleged that Rove's arguments have not fully prevailed in the GOP -- which is true. It is further alleged that these arguments have been discredited by events -- which is not true. The complications of Iraq have obscured Rove's victories, not undone them. And his key historical insight is unavoidable: Republicans win as conservative reformers.