“Sir, though I don’t encompass the minds of Buddhas past, future, and present, still I understand this by inference from the teaching. Suppose there was a king’s frontier citadel with fortified embankments, ramparts, and arches, and a single gate. And it has a gatekeeper who is astute, competent, and intelligent. He keeps strangers out and lets known people in. As he walks around the patrol path, he doesn’t see a hole or cleft in the wall, not even one big enough for a cat to slip out. He thinks, ‘Whatever sizable creatures enter or leave the citadel, all of them do so via this gate.’ In the same way, I understand this by inference from the teaching: ‘Those who are perfected ones, fully awakened Buddhas—whether past, future, or present—give up the five hindrances, corruptions of the heart that weaken wisdom. Their mind is firmly established in the four kinds of mindfulness meditation. They correctly develop the seven awakening factors. And they awaken to the supreme perfect awakening.’”