“Bhikkhus, if any bhikkhu understands as it really is: ‘This is suffering’ … ‘This is the way leading to the cessation of suffering,’ and then an ascetic or brahmin comes along—whether from the east, the west, the north, or the south—seeking an argument, searching for an argument, thinking: ‘I will refute his thesis,’ it is impossible that he could make that bhikkhu shake, quake, or tremble.
“Suppose, bhikkhus, there was a stone column sixteen yards long: an eight yards’ portion of it would be sunk in the ground, an eight yards’ portion above ground. Even if a forceful blast of wind comes along—whether from the east, the west, the north, or the south—the column would not shake, quake, or tremble. For what reason? Because it has a deep base and is securely planted.
“So too, bhikkhus, if any bhikkhu understands as it really is ‘This is suffering’ … ‘This is the way leading to the cessation of suffering,’ sn.v.446 and then an ascetic or a brahmin comes along … it is impossible that he could make that bhikkhu shake, quake, or tremble. For what reason? Because he has clearly seen the Four Noble Truths. What four? The noble truth of suffering … the noble truth of the way leading to the cessation of suffering.
“Therefore, bhikkhus, an exertion should be made to understand: ‘This is suffering.’… An exertion should be made to understand: ‘This is the way leading to the cessation of suffering.’”