Because: when you honor — as the devas, Indra — one from whom you might learn the Dhamma, he, learned, honored, confident in you, shows you the Dhamma. You, enlightened, heedful, befriending a teacher like that, practicing the Dhamma in line with the Dhamma, pondering, giving it priority, become knowledgeable, clear-minded, wise. But if you consort with a piddling fool who's envious, hasn't come to the goal, you'll go to death without having cleared up the Dhamma right here, with your doubts unresolved. Like a man gone down to a river — turbulent, flooding, swift-flowing — and swept away in the current: how can he help others across? Even so: he who hasn't cleared up the Dhamma, attended to the meaning of what the learned say, crossed over his doubts: how can he get others to comprehend? But as one who's embarked on a sturdy boat, with rudder & oars, would — mindful, skillful, knowing the needed techniques — carry many others across, even so an attainer-of-knowledge, learned, self-developed, unwavering can get other people to comprehend — if they're willing to listen, ready to learn. So: you should befriend a person of integrity — learned, intelligent. Practicing so as to know the goal, when you've experienced the Dhamma, you get bliss.