What is the purpose of the phrase "Thus shall your hearts be enlarged with kindness and benevolence towards them" in the paragraph above?
Banneker is using a metaphor to persuade Jefferson that if Jefferson was filled
with more of the emotions of kindness and compassion towards the slaves, then
he would oppose slavery.
Banneker is saying that if his readers' physical hearts were large enough, they
would care about the situation of the slaves.
Banneker is using figurative language to say that slaves are unhappy.
O Banneker is encouraging slaves to fight for their freedom.