Prosperity, in the context of paragraph 11, can be defined as the state of being successful and flourishing, particularly in terms of economic well-being and material wealth.
I determined the meaning of the word prosperity by considering the Latin suffix -ity, which indicates "the state of." In this case, the suffix suggests that prosperity refers to a state or condition. Considering the context of Mother Jones being described as someone who fought for workers' rights, it is likely that prosperity here refers to the state or condition of workers being successful and flourishing, particularly in terms of their economic well-being and material wealth.