What oratorical devices does King use to add vitality and force to his speech?

King usesand metaphors
in order to really paint a picture with his words and to capture and keep his audience's
attention. Imagery is the use of words to convey sensory
experience, and metaphors are comparisons where one thing is said
to figuratively be another. For example, in a particularly salient example, King
states,

One hundred years [after the Emancipation
Proclamation was signed] the life of the Negro is still badly crippled by the manacles of
segregation and the chains of discrimination. One hundred years later the Negro lives on a
lonely island of poverty in the midst of a vast ocean of material prosperity.

This description draws a vivid visual image of a black man or
woman bound by heavy iron manacles and roped with chains, captive on a desert island, in want,
while he or she continues to see white people all around who have everything they need and more.
It also compares the racial segregation to manacles (after all, "separate but equal"
was never remotely equal) and...