O'Neill establishes several images that address what it means to be human in the midst of modern industrialization. The social order intrinsic to 20th Century industrial civilization features an "upstairs" and "downstairs." Similar to the vessel upon which Yank toils, there is one group that inhabits the deck upstairs and another that live below. The two worlds do not meet. When they do coincide, neither fully understands the other. Mildred descends below and is horrified at what she sees. Yank walks amongst Fifth Avenue and is equally out of place. O'Neill's construction of the upstairs/ downstairs dynamic is reflective of how he sees the human predicament in 20th Century industrial civilization. There are people who have power on the upstairs level and those who don't in the downstairs one.
Another symbol that O'Neill uses in a deliberate manner is the cage. The very cage in which the ape lives and the setting where Yank dies is reflective of what it means to be poor in 20th Century industrialized society. O'Neill establishes that capitalism is a prison for those who are poor. There is little chance of social advancement, and even smaller hope of alleviating the suffering intrinsic to capitalist contraction and expansion. When capitalism expands, the rich gain more wealth and the poor are still kept in a subservient condition. When it contracts, the poor feel the effects in a much more deliberate manner than the wealthy. Industrial civilization that is driven by capitalism is one where the cage is a symbol that represents the experience of the poor. The symbol is meaningful in how it conveys the human predicament. Those who are wealthy have freedom and those who don't are in their own cages.
These symbols go very far in articulating the human predicament in industrialization. The Hairy Ape asserts that industrialized society in the 20th Century is constructed upon the accumulation of wealth. This operates as the organizing reality that determines the life that one leads. Social awareness of this dynamic causes unhappiness. When Mildred becomes aware of this "other," she is miserable. When Yank understands the reality that exists outside of the boiler room basement of the ship, he is miserable. Wealth and being conscious of how one lacks it are critical aspects to O'Neill's understanding of the human predicament in 20th Century industrialization. It is a reality in which individuals possess consciousness, an awareness of a world outside of their own. The inability to reconcile this reality with their own sense of identity is a critical part of the human predicament that O'Neill offers.
Finally, O'Neill suggests that one of the most painful aspects of the human predicament in 20th Century industrialization is that there is no solidarity. The accumulation of wealth has created such a brutal reality both within the individual and surrounding them that there can be no hopes of solidarity or connection. O'Neill shows this through Yank. Once Yank is aware of "the other," he is unable to find an collective entity in which he can live. He can no longer live on the bottom of the vessel because he knows how they see him. He is rejected by the wealthy, who seem him as an obstacle to overcome in imprisoning. Yank is also rejected by the Socialists, who see him as a spy. The only chance he sees at reconciliation and a sense of community is in the ape, himself. Yet, when the ape kills him, it reflects a reality that solidarity and absolute notions of collective identity is impossible in a world where the accumulation of wealth is the defining element. It is a reality in which Yank recognizes the "worst of both worlds:"
I ain't on oith and I ain't in Heaven, get me? I'm in de middel tryin' to seperate em, takin all de woist punches from bot' of 'em. Maybe dat's whay dey call Hell, huh?
Being aware of the "hell" that exists on Earth is one way in which O'Neill address the human predicament in industrial civilization.