What metaphors are used in Slave Ship by Amiri Baraka?

Much of the narrative is a metaphor for racial oppression. Baraka's one-act play, subtitled "a history pageant," presents a series of "historical tableaux" representing the conditions of slavery in the history of African Americans: the transportation of enslaved Africans on "slave ships" across the "Middle Passage" to America, the conditions of slavery on the Southern plantation, and the continuing struggle for racial equality. The white characters in the play include the disembodied voices of white slave traders on the slave ship, who laugh at the horrible conditions of the Africans they have captured and rape an African woman.