The Paper Bag Theory

I was reading on Wikipedia about those old "paper bag" parties where light-skinned Blacks openly discriminated against dark-skinned Blacks by denying them access to certain social functions based on the darkness of their complexion. Is our struggle with ill-feelings about being separated and given different jobs and responsibilities that were brought out through colorism but a dark period of our history with how to cope with racism or does xenophobia still interest me because I often wonder to what extent can individuals of a certain color discriminate against each other on hue and tone over long periods of time to begin with anyway? Part of what made it easier for light-skinned Blacks to do so in the mid-twentieth century was the fact that middle class and high-end office positions and other coveted jobs often went to those who were light-skinned or "high-yellow", a term that isn't used as often but was meant to describe lighter Blacks that could "pass for White", or gain entrance into worlds other Blacks weren't able to get into.