Ñ(VIII,200): This is the simile of the gate-keeper:
seyyathāpi dovāriko nagarassa anto ca bahi ca purise ‘‘ko tvaṃ, kuto vā āgato, kuhiṃ vā gacchasi, kiṃ vā te hatthe’’ti na vīmaṃsati.
Ñ: Just as a gate-keeper does not examine people inside and outside the town, asking 'Who are you? Where have you come from? Where are you going? What have you got in your hand?'—
Na hi tassa te bhārā,
Ñ: for those people are not his concern—
dvārappattaṃ dvārappattaṃyeva pana vīmaṃsati,
Ñ: but he does examine each man as he arrives at the gate,
evameva imassa bhikkhuno antopaviṭṭhavātā ca bahinikkhantavātā ca na bhārā honti,
Ñ: so too, the incoming breaths that have gone inside and the outgoing breaths that have gone outside are not this bhikkhu's concern,
dvārappattā dvārappattāyeva bhārāti ayaṃ dovārikūpamā.
Ñ: but they are his concern each time they arrive at the [nostril] gate itself.
Notes: the English translation does not translate 'ayaṃ dovārikūpamā', 'This is the simile of the gate-keeper'.