One advantage that Europeans had over Africans during the slave trade was

Europeans' conquest of Africa. One overwhelming advantage was the Europeans' technological superiority. The Maxim gun, invented in 1884, was the world's first automatic machine gun. European countries quickly acquired the Maxim, while the resisting Africans were forced to rely on outdated weapons.

so they can differentiate themselves from others as they saw themselves as the superior race. the star was basically a symbol that meant you are a less of a person than i am because of my race. the star was also degrading for those who had to wear it because they were aware of this and the nazis used the notion to make them feel less like a person.

bujías y una hora antes y no me parece muy difícil