Thambha: Obstinacy
Obstinacy is the heart stiffening against what it does not want to take in. Turning a heart to flint takes work, the way a fist has to be held closed, and this hardness was a deed repeated until the heart set that way on its own. Rain falling on stone runs straight off, and so does every word aimed at a heart kept like that.
Dovacassatā: Being hard to admonish
Being hard to admonish is the ear closing the moment correction starts. Prophet after prophet arrived, sent with words meant for the people's own good, and the hardening was arranged so precisely those words would find nothing to land on. Correction enters only where there is a crack, so anyone who cannot be told anything has no way left to learn.
Avijjā: Not knowing
Not knowing is the dark in which harm looks like ordinary business. Hardening came first and deafness followed, lest they might hear, so the blindness was chosen and then guarded, like a man who leaves an envelope sealed because he already knows the size of the bill inside. Ignorance kept this way stays comfortable for its owner and expensive for everyone else.
Karuṇā: Compassion
Compassion is the heart moving toward another's pain. The law shut out here was plain and practical: judge honestly, show mercy to your own brother, leave the widow, the orphan, and the stranger unoppressed. A heart hard enough to keep out the messenger is already hard enough to keep out the widow standing at its gate, and that is where the cost of flint gets paid.
Kammavipāka: The fruit of deeds
Deeds ripen into results of their own kind. That "therefore" carries the whole weight: great wrath grows out of years of stopped ears the way a field nobody plants comes back as a winter with nothing to eat. Zechariah speaks this to people newly home from exile, who had lived through the ripening and could count what it took.