Here was a population, low-class and mostly foreign, hanging always on the verge of starvation, and dependent for its opportunities of life upon the whim of men every bit as brutal and unscrupulous as the old-time slave drivers; under such circumstances immorality was exactly as inevitable, and as prevalent, as it was under the system of chattel slavery. Things that were quite unspeakable went on there in the packing houses all the time, and were taken for granted by everybody; only they did not show, as in the old slavery times, because there was no difference in color between master and slave.
This quote from Chapter 10 comes from Sinclair’s explanation of Ona’s working conditions; she is forced to work under Miss Henderson, who runs a prostitution ring, and most of her coworkers are prostitutes. Sinclair presents these conditions as a horrible situation for the modest, moral Ona but also offers an explanation in which the system of prostitution is examined in rough economic terms. As with every other failing among the working class in the novel, prostitution is shown not as an innate fault of the women involved but rather as the fault of the capitalists and the economic oppression that they force upon the impoverished immigrants. This passage also hints at the sexual oppression that young working girls are forced to endure from their bosses and foreshadows Ona’s rape at the hands of Phil Connor.
Additionally, the last sentence raises a Marxist argument about the appearance of calm surrounding social relations under capitalism. The argument runs that social relations under capitalism are no less exploitative than those that existed under slavery and in feudal societies but that capitalism conceals the true turbulent nature of these relationships under a veneer of naturalness and inevitability. The difference between wage labor and these antiquated forms of subjugation is only a matter of transparency; though the “difference in color between master and slave” is no longer applicable to the owner-laborer relationship, the oppression remains the same.