What are the motifs in The Iron Heel by Jack London?

Common humanity is a reoccurring idea in the story. Throughout the book, there are references to ways in which the opposing sides of the central socialist/capitalist conflict share perspectives and take generally similar actions as manifestations of those perspectives. The first is referenced by Everhard in chapter two, in which he refers to human beings in general, and both capitalists and socialists in particular, as being fundamentally selfish. This is the only fully overt reference to humanity's ultimate commonality throughout the book, but it is not the only reference.