“Frederick Douglass (born Frederick Augustus Washington Bailey, c. February 1817 or 1818 – February 20, 1895) was an American social reformer, abolitionist, orator, writer, and statesman. After escaping from slavery in Maryland, he became a national leader of the abolitionist movement in Massachusetts and New York, becoming famous for his oratory and incisive antislavery writings. Accordingly, he was described by abolitionists in his time as a living counterexample to enslavers’ arguments that enslaved people lacked the intellectual capacity to function as independent American citizens. Northerners at the time found it hard to believe that such a great orator had once been enslaved. It was in response to this disbelief that Douglass wrote his first autobiography.”
https://en.wikipedia.org/wiki/Frederick_Douglass
Frederick Douglass, like his contemporary, Abraham Lincoln, pretty much taught himself how to read. Imagine the brain power required to pull something like that off.
Because he lacked the formal education of his time, his autobiography is very readable to today’s reader. He doesn’t go for the elaborate flourishes common to writers of his time.