When the 40th president of the United States died in 2004, former British Prime Minister Margaret Thatcher told mourners at his funeral that "Ronald Reagan knew his own mind. He had firm principles and, I believe, right ones. He expounded them clearly. He acted upon them decisively. When the world threw problems at the White House, he was not baffled or disorientated or overwhelmed. He knew almost instinctively what to do."

Had Reagan outlived Lady Thatcher, he could have described her with the same bracing clarity that marked so much of the public life of Britain's longest-serving prime minister of the 20th century, who died yesterday at the age of 87 after a stroke.

The daughter of a middle-class grocer, Thatcher earned her way to Oxford in 1943, where she was exposed to the classically liberal economic and political ideas of Friedrich Hayek. By 1946, she was president of the Oxford University Conservative Association. Then, after working on the team of scientists that created soft-serve ice cream (she majored in chemistry), she stood for office in 1951. "I am a conviction politician," she said often thereafter. "I believe in certain things."

A great communicator on par with Reagan, her own words best explain what she believed: "Socialism started by saying it was going to tax the rich, but very rapidly it was taxing the middle-income groups," Thatcher said in 1976 as the leader of the Tory opposition. "Socialist governments traditionally do make a financial mess," she continued. "They always run out of other people's money."

Later, after securing her first re-election in 1983, Thatcher told her party, "One of the great debates of our time is about how much of your money should be spent by the State and how much you should keep to spend on your family. Let us never forget this fundamental truth: The State has no source of money other than money which people earn themselves."

"Prosperity will not come by inventing more and more lavish public expenditure programmes," she continued. "You do not grow richer by ordering another cheque-book from the bank." And she responded to liberal demands to "spread the wealth" by saying of an opponent during debate in the House of Commons that "yes, he would rather have the poor poorer, provided that the rich were less rich. That is the liberal policy."

Her decade at 10 Downing Street was marked by many great triumphs and some bitter struggles. She was first elected in 1979 amid the Winter of Discontent, when Britain's economy was at the paralyzing mercy of radical left-wing unions that called strikes at the slightest whim. She sternly faced them down, then went on to privatize state-owned industries, reviving Britain's waning entrepreneurial energies. After that, she restored Britain's national spirit by winning the Falklands War. She signed the 1985 Anglo-Ireland Agreement that ultimately ended Northern Ireland's Troubles. And her decision to put tactical nuclear weapons in Britain in concert with the U.S. in 1982 prompted the Soviets to call her "the Iron Lady." Of such rare mettle are worthy convictions tempered and enduring honors confirmed.