In 'The Hairy Ape' the audience is brought face to face with some of the worst fears of prosperous, genteel society. There are the obvious fears such as those of poverty, loss of wealth, loss of control and the physical fear of brute strength. Then there are other, more subtle fears (some barely admitted to by the well-to-do) such as not wanting to share prosperity with a proletariat who could grab all the wealth from the intelligent but lily-livered intelligentsia by sheer physical dominance and strength of numbers. In that, we see the fear of being overcome or overwhelmed by our 'subordinates.' Another subtle fear is the fear of entrapment and this applies to both individual entrapment such as Yank slaving in the stinking heat of the stokehole but also the general entrapment of a mankind 'born free but forever in the chains' of self-imposed wage slavery and mortgages.
These fears are presented for the audience to experience and share in a number of ways. For example there is the vivid imagery in the stinking sweaty heat of the stokehole - we can almost feel the blast and smell the stench of the stale toilet-less air gust upwards as Mildred is brought face to face with the sheer essence of a base kind of Neanderthal manhood. This is made all the worse by the contrast with her over-protection from the world of men and labor as it blows her fake illusions of superficial social work away. The image of her costume is also effective in transmitting fear to the audience. The soft, white floaty fabric of her dress could be so easily 'soiled' by the sooty smuts and grubby sweaty stagnant air from the stokehole. Horrors - the blackened unwashed men could almost reach out and touch it - a nauseating thought for many in the audience. It is almost as if the audience are terrified that the young 'lady' herself will be forever contaminated by her association with Yank, the 'beast' of the stokehold - a primeval fear for many of us. This is apt because he, of course, represents the most primeval being the writer could invent.
A pivotal moment in The Hairy Ape, of course, is that instant in which a vociferous, cursing Yank, with a black-smudged back on which rivulets of sweat run, around whose eyes "the coal dust sticks like black make-up, giving [him] a queer, sinister expression" turns in hot rage over the whistling from the bridge only to be vis-a-vis with a "white apparition" that is horrified by the sight of him, calling him "a hairy ape." But, the real terror is that she is involved in an existential confrontation.
For all her nonchalant allusions to her grandfather intended more to irritate her supercilious aunt than to express any admiration for her ancestor, the pale, vacuous young woman realizes that she does not possess the mettle or earthy honesty of her ancestor:
I would like to be sincere; to touch life somewhere. But I'm afraid I have neither the vitality nor integrity. All that was burnt out in our stock before I was born. Grandfather's blast furnaces, flaming to the sky, melting steel, making millions--then father keeping those home fires burning, making more millions--and little me at the tail end of all. I'm a waste in the Bessemer process.
When, therefore, Mildred is confronted by Yank, the primordial creature of dead generations, "the hairy ape," she faces what her grandfather may have been closer to. It is a brutality and a raw strength, but it is also honest and real. And, this existential realization terrifies Mildred because she is weak and pretentious and truly what her aunt has called her, though for a different reason: "poser."