TRAINED as a lawyer at the prestigious Harvard Law School, and having worked as a civil rights attorney, US president Barack Obama is adept at thinking on his feet. But what makes him such a charismatic speaker is his grasp of rhetoric.

Rhetoric is the art or study of using language effectively and persuasively. Masters of rhetoric include Greek philosophers Aristotle and Plato, British prime minister Winston Churchill, civil rights leader Martin Luther King and former US president John F. Kennedy.

Here are some rhetorical devices used by gifted speakers like Rev King and Mr Obama.

1. Anaphora

This is the repetition of the same word or phrases at the beginning of successive sentences. The best example of this is in Martin Luther King’s “I Have a Dream” speech delivered on August 28, 1963, at the Lincoln Memorial in Washington, DC, which is the world’s most quoted shout for freedom and equality.

Said Dr King: “I have a dream that one day this nation will rise up and live out the true meaning of its creed: We hold these truths to be self-evident, that all men are created equal.”

Eight more paragraphs starting with the words “I have a dream” follow, sketching out Dr King’s vision of a future where blacks and whites can live side by side as equals.

The effect of this is to reinforce an idea over and over again.

In his victory speech at the Iowa caucus, Mr Obama employed this effect when he said: “You have done what the cynics said we couldn’t do. You have done what the state of New Hampshire can do in five days. You have done what America can do in this New Year.”

2. Epistrophe

The opposite of anaphora, this is the repetition of a word or expression at the end of successive sentences. In 1863, President Lincoln exploited this rhetorical tool when he envisioned a government “of the people, by the people, and for the people.”

In Mr Obama’s Jan 8, 2008 speech in New Hampshire, he used the expression “Yes, we can” as an epistrophe: “It was whispered by slaves and abolitionists as they blazed a trail towards freedom through the darkest of nights: Yes, we can. It was sung by immigrants as they struck out for distant shores and pioneers who pushed westward against an unforgiving wilderness: Yes, we can.”

The phrase became a victory chant on the night he was elected America’s 44th president.

3. Alliteration

This is the repetition of the same sounds at the beginning of words or in stressed syllables, and the purpose is to make phrases sound catchy, and hence, memorable to listeners. In 2005, at Knox College, Mr Obama described America as “a place where destiny was not a destination, but a journey to be shared and shaped…”

4. Antithesis

This is juxtaposing two phrases in order to show the great contrast of actions. John F. Kennedy famously used antithesis to great effect in his inaugural speech: “My fellow, Americans, ask not what your country can do for you; but ask what you can do for your country.”

Mr Obama used antithesis to underline the theme of change in his speech announcing his presidential bid on Feb 10, 2007 when he said: “In the face of war, you believe there can be peace. In the face of despair, you believe there can be hope.”

When using antithesis, balance the number of words on either side and finish on a positive note. This will make your use of antithesis both powerful and memorable.

5. The magic of three

The grouping of things in threes seems to resonate with people — lock, stock and barrel; blood, sweat and tears; earth, wind and fire. Julius Caesar famously proclaimed: “Veni, Vidi, Vici” — Latin for “I came, I saw, I conquered”.

Mr Obama also used this magical grouping as he promised to find Americans jobs “at a decent wage”, health care “you can afford” and a “retirement that is dignified”.

He added: “Today, I say to you that the challenges we face are real, they are serious and they are many.”

In his 2004 speech at the Democratic National Convention that brought him the attention of the world, he declared that, “there is not a black America and a white America. There’s the United States of America.”

In inspiring his listeners and gathering their support, Mr Obama was walking in the footsteps of a long line of orators, starting from the ancient Greeks who used triple repetitions in their arguments to increase their persuasion force.