What important point does this part of olaudah equiano's narrative show about slavery?

You didn't show us the part of a speech you have in view, but let me refer you to another answer I posted recently about Olaudah Equiano.  

Olaudah Equiano's autobiography was published in 1789 with the title, "The Interesting Narrative of the Life of Olaudah Equiano, or Gustavus Vassa, the African."   Kidnapped and sold into slavery at about age 11 in Africa, Equiano (who was given the name "Gustavus Vass" by one of his eventual owners as a slave), recounted in his memoirs the wretched experience of being brought to the Americas on a slave ship, as well as his experiences as a slave in the Caribbean, Europe and America.  (He was bought by several different owners over time.)  His last owner, Robert King, allowed Equiano to work to buy his freedom, and by 1768 he did so and went to England.
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