Rhetorical devices

Repetition 

In the “Audacity of Hope” speech, Obama mainly uses repetition to draw attention to the points that he wants the audience to remember easily. When he talks about the faith of Americans, he uses the repetition “that we can” to show that the country believes in the concept of the American Dream:

That is the true genius of America, a faith in the simple dreams of its people, the insistence on small miracles. That we can tuck in our children at night and know they are fed and clothed and safe from harm. That we can say what we think, write what we think, without hearing a sudden knock on the door. That we can have an idea and start our own business without paying a bribe or hiring somebody's son…

Here the repetition also urges the audience to feel grateful since they live in a country that is safe and free of corruption and where rights such as free speech are guaranteed to everyone.

On the same note, Obama uses the repetition “more to do” to acknowledge that they still have a lot of work to do to make America an even better country than it already is:

… I say to you tonight: we have more work to do. More to do for the workers I met in Galesburg, Illinois (…) More to do for the father I met...