Giuseppe Pellizza da Volpedo. The Fourth estate (orig., The Path of Workers), 1898-1901.
This monumental work has become one of the most important images of labor in the history of painting. It was done in a very subtle Divisionist style and is really even a little murkier than this reproduction. It depicts the moment 3 negotiators emerge from a mass of laborers on strike.
It's a complicated work with much history, and its own Wikipedia page:
https://en.wikipedia.org/wiki/The_Fourth_Estate_%28painting%29
#Painting