"All races and varieties of men are improvable. This is the grand distinguishing attribute of humanity, and separates man from all other animals. If it could be shown that any particular race of men are literally incapable of improvement, we might hesitate to welcome them here. But no such men are anywhere to be found, and if they were, it is not likely that they would ever trouble us with their presence. ... I know of no rights of race superior to the rights of humanity, and when there is a supposed conflict between human and national rights, it is safe to go the side of humanity."