what allusin doe douglass present to show that slaves are not any lesser human being?

I'm looking for a direct allusion but can't see one. I think Douglass's mother was very much an angel, like many mothers, in that she came to him when she could at night.

"She was with me in the night. She would lie down with me, and get me to sleep, but long before I waked she was gone. Very little communication ever took place between us. Death soon ended what little we could have while she lived..."