The theory that taught only the strong survived
Plessy v. Ferguson- basically Louisiana passed a law saying the black people need it separate car when traveling on train not on the same as a white person.
Plessy was 1/8 African descent (was born free and other 7/8 was of European descent ) and under Louisiana rule he had to sit on a black car. eventually he sat on white only car and got into trouble, just like Rosa Parks. and he was eventually got arrested and tried.
