What evidence does douglass provide to prove that slavery is immoral?

Douglass’s Narrative shows how white slaveholders perpetuate slavery by keeping their slaves ignorant. At the time Douglass was writing, many people believed that slavery was a natural state of being. They believed that blacks were inherently incapable of participating in civil society and thus should be kept as workers for whites. The Narrative explains the strategies and procedures by which whites gain and keep power over blacks from their birth onward. Slave owners keep slaves ignorant of basic facts about themselves, such as their birth date or their paternity. This enforced ignorance robs children of their natural sense of individual identity. As slave children grow older, slave owners prevent them from learning how to read and write, as literacy would give them a sense of self‑sufficiency and capability. Slaveholders understand that literacy would lead slaves to question the right of whites to keep slaves. Finally, by keeping slaves illiterate, Southern slaveholders maintain control over what the rest of America knows about slavery. If slaves cannot write, their side of the slavery story cannot be told. Wendell Phillips makes this point in his prefatory letter to the Narrative

Ithink its trade and commernce let me know if im wrong