The chapter opens mid-argument. An imagined voice mocks him: "Ha, ha, ha! You will be finding enjoyment in toothache next." He answers flatly: yes, even in toothache there is enjoyment. He had it for a whole month and can confirm.
What makes toothache different from ordinary pain, he argues, is that the moans it produces are not candid, they are malignant. The malignancy is the whole point. If the sufferer found no enjoyment in moaning, he wouldn't moan. The moans express several things at once: the aimless humiliation of pain that has no enemy attached to it, the consciousness of being in complete slavery to one's own teeth, the knowledge that if someone wished it your teeth would stop aching and if not they'd go on for three more months, and that your only recourse is to beat the wall with your fist.
Here is the crucial distinction he draws. A coarse peasant moans simply because he hurts. The educated man of the nineteenth century, "divorced from the soil and the national elements", moans differently on the second and third day. His moans acquire trills and flourishes. They become disgustingly malignant and go on for days. He knows perfectly well he is doing himself no good. He knows his family is listening with loathing, doesn't believe him, understands he could moan more simply. He continues anyway, and in all those recognitions and disgraces lies what the Underground Man calls "a voluptuous pleasure."
He then gives that pleasure a voice. The imagined monologue of the moaner: "I am worrying you, I am lacerating your hearts... I am not a hero to you now, as I tried to seem before, but simply a nasty person, an impostor. Well, so be it, then! I am very glad that you see through me."
The chapter closes on a question that lands like a verdict: his jests, he admits, are in bad taste, jerky, lacking self-confidence. The reason? He does not respect himself. He leaves it there, and asks whether any man of genuine perception could.
Coming Up in Chapter 5
Having explored the pleasure found in pain, the Underground Man will dig even deeper into the psychology of the self-aware sufferer, revealing more uncomfortable truths about human nature and consciousness.