The Underground Man opens with a question he left hanging at the end of Chapter 1: why couldn't he even become an insect? He tried, he says, many times, and wasn't equal to even that. His answer: too much consciousness. He declares it plainly, to be too conscious is a real illness. Ordinary men, men of action, get along fine with a fraction of his awareness. He has far too much of it, and it's destroying him.
The strangest evidence he offers: the more acutely he felt what was "sublime and beautiful," the deeper he simultaneously sank into ugly, shameful behavior. Not as cause and effect, as parallel motion. Awareness of the good did not prevent the bad; it seemed to accompany it. The shame that followed would gnaw at him, consuming him in bitterness, and then something terrible happened. The bitterness would turn into "a sort of shameful accursed sweetness" and finally into what he can only call real enjoyment. He insists on this word, repeating it: enjoyment, enjoyment. The pleasure came specifically from the intense consciousness of his own degradation, from knowing he had hit the last barrier, that it was horrible, that there was no escape, and that he probably would not wish to change even if he could.
He extends this logic to its endpoint: over-acute consciousness produces inertia, and inertia means not just hesitation but the complete inability to do anything at all. He even notes the grim absurdity, this means one can't be blamed for being a scoundrel, because it follows from the laws of consciousness itself. Though he adds: that's cold comfort once you realize you actually are one.
The chapter closes with a sketch of his pride. He has enormous amour propre, suspicious, quick to take offense, thin-skinned as "a humpback or a dwarf." He then floats a scenario that captures his psychology precisely: if someone slapped him in the face, he thinks he might actually be glad of it. Not from masochism exactly, but because even humiliation contains its own intense enjoyment when you are sufficiently conscious of your hopeless position. And yet, even then, he could never have brought himself to seek revenge. Not because he forgave, but because he could never make up his mind to do anything. That, he promises, is what he will explain next.