Sally Kohn: Mark and Ingalls Wright quote, differences of age and sex have no longer any distinctive social validity for the working class. All are instruments of labor, more or less expensive to use, according to their age and sex. But does this analysis point to something important about the way that classes lived under capitalism? She says it's not just a question of adding gender in class but because some of these axes of oppression are systemically having an impact on the fundamental dynamics at play.