The Spirits' Book
Book Three - Moral Laws
Chapter X - IX. Law of Liberty
831. Does the natural inequality of aptitudes place some members of the human race under the control of more intelligent members?
“Yes, so that they may rise to a higher level, but not to further degrade them by slavery. People have too long viewed certain ethnic groups as working animals with arms and hands, and believed they have the right to use them and sell them like beasts. They think that they are of purer blood, when they are really fools! Only the spirit is the marker of purity, not blood.” (See Q361-803)