The idea of "Separate but equal" was to offer equal protection to all people under law.
Explanation:
The separate but equal is nothing but a legal doctrine passed by the constitutional law of united states which offers "equal protection" to people of all race.
It violates the rules of racial segregation between the blacks and whites and intend to make them share same service such as housing,transportation and medical care.
It also stood against the racial segregation in the field of education and employment.
These are the ideas and goals of "Separate and equal".