San Francisco  - Poet and playwright Elizabeth Alexander will be only the fourth poet to be featured at a presidential inauguration on Tuesday.

Alexander, an African-American professor at Yale University, said that she started writing the inaugural poem about a month ago and that Obama's decision to include a poet in the ceremony reflected his recognition of the power of words.

"I think that the fact that President-elect Obama has decided to have a poem in this ceremony is a wonderful affirmation to the power of language, the way in which poetry gives us distilled and mindful and careful language that can both give us a moment of pause, a moment of contemplation and that can also ... look at the world from a slightly different angle," she told CNN.

The previous inaugural poets were Robert Frost at the 1961 inauguration of John F Kennedy in , and Maya Angelou and Miller Williams who read at Bill Clinton's inaugurations in 1993 and 19997.

Born in Harlem, New York in 1962, Alexander first came to Washington as a toddler when her parents brought her to the Lincoln Memorial to hear Martin Luther King Jr's famous 1963 I have a Dream speech.

Her father was a civil rights adviser to President Lyndon Johnson, and later the Secretary of the Army under President Jimmy Carter. Her mother teaches history at George Washington University and that visit to Washington framed her entire life.

"Throughout the years, that became an important, iconic story in our family," Alexander said. "A way of saying, 'This is what you do when you think that things should be better. You work, you march, you do and contribute what you have to contribute.' So the day after Dr King's birthday, to be in that very spot and for me also to be in the great city that I grew up in is going to be very powerful."

Alexander has published five books of poetry and was nominated for a Pulitzer Prize in 2005. She hopes that her inaugural poem will allow people a moment of reflection amid the joyous celebrations.

"I am hoping to offer language that will give people a moment of pause," Alexander said. "That there is almost a quiet pool in which they are able to stand and think for a moment. I think that's part of what poetry does. It arrests us." (dpa)