As soon as he screams at his wife, Ivan knows he has reached the end, and he still has no answer to his questions.
He starts to scream and thrash without stopping, and continues for the next three days.
At first Ivan screams, "Oh, oh! I won't!" over and over again, but eventually just falls into screaming the letter O.
He refuses to die, even though he knows he can't resist anymore.
The thought that his life had been a good one keeps him from dying.
Once again Ivan feels as if he's being shoved through a long, narrow, dark sack but can't reach the bottom.
He has the sense that he can't fall through because he won't give up the idea that his life was good. A part of him still resists.
Then, suddenly on the third day (the narrator doesn't tell us exactly when this happens), Ivan feels struck in the chest and side, and at that moment falls through the bottom of the sack to find light.
He stops screaming.
Ivan now admits to himself that none of his life was "the right thing" (12.5), but also finds a confidence within himself that he can fix things.
But how? What would the right thing be?
Just before this revelation, the narrator tells us, Ivan's son Vasya had crept up to him. Ivan was still screaming and flailing, and when his hand had fallen on Vasya's head, Vasya had held it, kissed it, and started crying.
It was at this moment that Ivan had his realization.
Ivan only notices Vasya's kiss after having his realization.
Ivan then looks at his crying son. And something amazing happens: Ivan Ilych feels sorry for him.
He also notices Praskovya Fedorovna, who has come up to him, tears on her face. And for the first time he feels sorry for her too.
Ivan sees that his suffering is very hard on them, and that it will be better for them now if he dies.
He wants to say this, but doesn't have the strength. He only manages to tell Praskovya Fedorovna to take Vasya away, and to say, "sorry for him…sorry for you too" (12.8).
Ivan also tries to say "Forgive me," but can only manage "Forego…"
And suddenly Ivan finds that he is no longer tortured. He's free.
All he has to do is release his family, and himself, from his sufferings. "How good and how simple" (12.9), he thinks to himself.
Ivan wonders what has happened to his pain, and finds that it is still there, but it doesn't matter to him.
His fear of death is gone completely. In its place, there is only light. Ivan exclaims aloud "What Joy!" (12.15).
The narrator tells us that Ivan experienced all of this as a single instant. The others watching him see his body continue to die in agony for two hours, its gasps and rattles gradually fading away.
Finally, someone exclaims: "It is finished," and Ivan repeats it to himself "in his soul" (12.17). "Death is finished," he says. "It is no more" (12.19).