Answer:
that slavery is wrong for him.
Step-by-step explanation:
Frederick Douglass was an American abolitionist, author, social reformer, statesman and public speaker, popularly known for his advocacy against slave trade or slavery. He was born in February at Talbot County, Maryland, United States of America.
Frederick was fortunate to escape slavery in Maryland and subsequently, he became the national leader in the abolitionist movement established in New York and Massachusetts with the sole intention or purpose of abolishing slavery before and during the American Revolutionary War.
According to Frederick Douglass, there "is not a man beneath the canopy of heaven" who does not know that slavery is wrong for him. This simply means that everyone in the universe is aware of the fact that slavery is wrong and should be abolished or put to an end.