4 ideas
Dhritarashtra, unable to sleep before the war, summons his low-born half-brother Vidura and hears through the night exactly why his sons' injustice to the Pandavas will destroy his line. He agrees with nearly every maxim and changes nothing, because acting on the advice would mean restraining the sons he loves. The episode shows that a ruler can fully understand a warning and still ignore it when heeding it costs him an attachment.
Vidura lists eight qualities that make a person illustrious: wisdom, good birth, self-control, learning, courage, measured speech, giving according to one's means, and gratitude. The list puts inner discipline and conduct beside inherited status, so birth becomes one factor among eight rather than the whole measure of a person.
Advice should be judged by what the adviser stands to gain from your decision, not by how persuasive or loyal they seem. Counselors whose fortunes rise with your mistakes, like the flatterers around Duryodhana, will steer you toward those mistakes, so a king must keep them out of deliberation however close they are.
Vidura treats anger as a force that destroys the person who harbors it before it touches its target. It clouds judgment, turns allies into enemies, and pushes one into irreversible acts, so the one who swallows anger is counted wiser and stronger than the one who vents it. Read this way, restraint is a form of self-protection and practical advantage, not weakness.