“I invent nothing,” claimed Auguste Rodin, “I rediscover.” It was in this spirit that Stephen Harper, addressing the Canadian Parliament in 2003 on the threat posed by Saddam Hussein, rediscovered a speech delivered in Canberra two days previously by John Howard, then Australia's Prime Minister. So closely did Harper mimic passages of Howard's speech that the only obvious difference was his inspired substitution of the word “Canada” for “Australia”.

Opposition researchers have only now, in the middle of a general election campaign, revealed the similarities, damaging Mr Harper's hope of returning as Prime Minister. The surprise, surely, is that he did not find a more stirring speech to rip off.

Many of history's greatest orators have been blatant plagiarists. Even 45 years after its delivery, Martin Luther King's “I have a dream” speech of 1963 still has the power to lift the human spirit. Yet the passage in which he kept repeating the defining phrase was not in his prepared script but made up on the spur of the moment.

Or so it seemed. In fact, Dr King had already used the phrase several times in the previous months. Nor was it originally his dream. The refrain had been used in September 1962 by Prathia Hall, an activist with the Student Nonviolent Coordinating Committee, during a prayer service near Albany. Yet, as Hall later put it, King “did far more with it than I could have done”.

What was more, in choosing a peroration that referred to My Country 'tis of Thee, King ended his “I have a dream” speech with words that closely resembled those delivered in 1952 by the black lawyer and politician Archibald Carey.

Carey had fired-up the Chicago Republican Convention with “Let freedom ring, not only from the Green Mountain and White Mountains of Vermont and New Hampshire; not only from the Catskills of New York; but from the Ozarks in Arkansas; from the Stone Mountain in Georgia...”

Without acknowledging this source, King's version was more lyrical: “Let freedom ring from the prodigious hilltops of New Hampshire. Let freedom ring from the mighty mountains of New York... But not only that, let freedom ring from Stone Mountain of Georgia.”

Sometimes it is the man and the moment, rather than the originality of expression, that makes for rousing oratory. Stephen Harper's problem is that he is no Martin Luther King.

Graham Stewart is the author of His Finest Hours: the War Speeches of Winston Churchill

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