What are some examples of metaphor in Martin Luther King's "I Have a Dream" speech?

Some of the metaphors in Martin Luther King's "I Have a Dream" speech include "beacon light of hope," which uses light as a metaphor for hope, and "long night of captivity," which represents the years of enslavement African-Americans faced. Metaphors are featured throughout the speech, with a heavy emphasis on light and dark.

Other metaphors in Martin Luther King's "I Have a Dream" speech include:

• "Seared in flames of withering injustice," which compares injustice to the flames of a fire.
• "Joyous daybreak" ending the "long night of their captivity," which uses light to symbolize freedom and night to represent enslavement.
• "Lonely island of poverty," uses an island to represent poverty, and therefore isolation. This is followed by "vast ocean of material prosperity," which compares material prosperity to an ocean.
• "To cash a check" refers to African-Americans coming to claim the freedom they were promised; this is complemented by "signing a promissory note," which refers to the freedom promised by the founding fathers under the Declaration of Independence. The speech then states that every American was to "fall a heir" to this independence, highlighting how not all Americans have benefited from the Declaration of Independence.
• "Storms of persecution" highlights how being persecuted as an African-American was stormy.