Then a certain bhikkhu approached another bhikkhu, and after approaching, he said to that bhikkhu: "To what extent, friend, is a bhikkhu's vision well purified?"

"Friend, when a bhikkhu knows, as it truly is, the arising and passing away of the six sense bases, to that extent, friend, a bhikkhu's vision is well purified."

Then that bhikkhu, dissatisfied with the explanation given by the other bhikkhu, approached another bhikkhu. After approaching, he said to that bhikkhu: "To what extent, friend, is a bhikkhu's vision well purified?"

"Friend, when a bhikkhu knows, as it truly is, the arising and passing away of the five aggregates that are subject to being held onto as a self, to that extent, friend, a bhikkhu's vision is well purified."

Then that bhikkhu, dissatisfied with the explanation given by the other bhikkhu, approached still another bhikkhu. After approaching, he said to that bhikkhu: "To what extent, friend, is a bhikkhu's vision well purified?"

"Friend, when a bhikkhu knows, as it truly is, the arising and passing away of the four great elements, to that extent, friend, a bhikkhu's vision is well purified."

Then that bhikkhu, dissatisfied with the explanation given by the other bhikkhu, approached still another bhikkhu. After approaching, he said to that bhikkhu: "To what extent, friend, is a bhikkhu's vision well purified?"

"Friend, when a bhikkhu knows, as it truly is, 'whatever is subject to arising, all that is subject to ending,' to that extend, a bhikkhu's vision is well purified."

Then that bhikkhu, dissatisfied with the explanation given by the other bhikkhu, approached the Blessed One. After approaching, he said to he Blessed One: "Venerable sir, here I approached a certain bhikkhu and said to him: 'To what extent, friend, is a bhikkhu's vision well purified?' When this was said, venerable sir, that bhikkhu replied to me: 'Friend, when a bhikkhu knows, as it truly is, the arising and passing away of the six sense bases, to that extent, friend, a bhikkhu's vision is well purified.' Dissatisfied with the explanation given by that bhikkhu, I approached another bhikkhu and said to him: 'To what extent, friend, is a bhikkhu's vision well purified?' When this was said, venerable sir, that bhikkhu replied to me: 'Friend, when a bhikkhu knows, as it truly is, the arising and passing away of the five aggregates that are subject to being held onto as a self, to that extent, friend, a bhikkhu's vision is well purified.' Still dissatisfied with the explanation given by that bhikkhu, I approached still another bhikkhu and said to him: 'To what extent, friend, is a bhikkhu's vision well purified?' When this was said, venerable sir, that bhikkhu replied to me: 'Friend, when a bhikkhu knows, as it truly is, the arising and passing away of the four great elements, to that extent, friend, a bhikkhu's vision is well purified.' Still dissatisfied with the explanation given by that bhikkhu, I approached still another bhikkhu and said to him: 'To what extent, friend, is a bhikkhu's vision well purified?' When this was said, venerable sir, that bhikkhu replied to me: 'Friend, when a bhikkhu knows, as it truly is, 'whatever is subject to arising, all that is subject to ending,' to that extent, a bhikkhu's vision is well purified.' Dissatisfied with the explanation given by that bhikkhu, venerable sir, I have now approached the Blessed One. Venerable sir, to what extent is a bhikkhu's vision well purified?"

"Suppose, bhikkhu, a man had never seen a kiṁsuka tree before. He might approach another person who knows about the kiṁsuka tree and ask: 'What is the kiṁsuka tree like, sir?'

That person might reply: 'Good man, the kiṁsuka tree is black, like a burnt stump.' At that time, bhikkhu, the kiṁsuka tree might have been exactly as that person had seen it.

Bhikkhu, suppose that man, dissatisfied with the explanation given by the first person, approached another person who knows about kiṁsuka tree and asked: 'What is the kiṁsuka tree like, sir?' That person might reply: 'Good man, the kiṁsuka tree is red, like a lump of meat.' At that time, bhikkhu, the kiṁsuka tree might have been exactly as that person had seen it.

Then, bhikkhu, suppose that man, still dissatisfied with the explanation given by the second person, approached another person who knows about the kiṁsuka tree and asked: 'What is the kiṁsuka tree like, sir?' That person might reply: 'Good man, the kiṁsuka tree has hanging bark strips and has burst seed pods, like a sirīsa tree.' At that time, bhikkhu, the kiṁsuka tree might have been exactly as that person had seen it.

Then, bhikkhu, suppose that man, still dissatisfied with the explanation given by the third person, approached another person who knows about the kiṁsuka tree and asked: 'What is the kiṁsuka tree like, sir?' That person might reply: 'Good man, the kiṁsuka tree is dense with leaves and foliage, providing abundant shade, like a banyan tree.' At that time, bhikkhu, the kiṁsuka tree might have been exactly as that person had seen it.

In the same way, bhikkhu, those noble persons each answered according to what they were focused on when their vision was well purified.

Suppose, bhikkhu, a king had a border city with solid fortifications, a strong encircling wall and gateways with gates at six points. In that city, there is a wise, experienced, and discerning gatekeeper who prevents the entry of strangers and admits those who he knows.

From the eastern direction, a swift pair of messengers might approach that gatekeeper and say: 'Good man, where is the lord of this city?'

He would reply: 'Venerable sirs, he is sitting in the central hall.'

Then that swift pair of messengers would accurately deliver a message of reality to the lord of the city and leave by the route by which they had arrived.

From the western direction, a swift pair of messengers might approach that gatekeeper and say: 'Good man, where is the lord of this city?' He would reply: 'Venerable sirs, he is sitting in the central hall.' Then that swift pair of messengers would accurately deliver a message of reality to the lord of the city and leave by the route by which they had arrived.

From the northern direction, a swift pair of messengers might approach that gatekeeper and say: 'Good man, where is the lord of this city?' He would reply: 'Venerable sirs, he is sitting in the central hall.' Then that swift pair of messengers would accurately deliver a message of reality to the lord of the city and leave by the route by which they had arrived.

From the southern direction, a swift pair of messengers might approach that gatekeeper and say: 'Good man, where is the lord of this city?' He would reply: 'Venerable sirs, he is sitting in the central hall.' Then that swift pair of messengers would accurately deliver a message of reality to the lord of the city and leave by the route by which they had arrived.

Bhikkhu, this simile has been given by me to convey a meaning. And this is the meaning here:

'City,' bhikkhu, is a designation for this body composed of the four great elements, originating from mother and father, sustained by rice and porridge, subject to instability, rubbing, pressing, injury, and falling apart.

'Six gates,' bhikkhu, is a designation for the six internal sense bases.

'Gatekeeper,' bhikkhu, is a designation for mindfulness.

'Swift pair of messengers,' bhikkhu, is a designation for tranquility and insight.

'Lord of the city,' bhikkhu, is a designation for consciousness.

'Central square,' bhikkhu, is a designation for four great elements—earth element, the water element, the fire element, and the air element.

'Message of reality,' bhikkhu, is a designation for Nibbāna.

'Route by which way they had arrived,' bhikkhu, is a designation for the Noble Eightfold Path, i.e.—right view, right resolve, right speech, right action, right livelihood, right effort, right mindfulness, and right collectedness."