1"Bhikkhus, there are these three faculties. What three? The faculty ‘I shall know the as-yet-unknown,’ the faculty of final knowledge, the faculty of one endowed with final knowledge. These are the three faculties." [n.206] This sutta is also at It 62, with the addition of verses that partly help to clarify the meaning. The three faculties are formally defined at Vibh 124, but more concisely than in Spk, which explains: The faculty "I shall know the as-yet-unknown" (anaññataññassāmītindriya) is the faculty arising at the moment of the path of stream-entry in one practising with the thought, "I will know the Dhamma I have not known before in beginningless saṁsara." The faculty of final knowledge (aññindriya) is the faculty arisen on the six occasions from the fruit of stream-entry on (through the path of arahantship); it occurs in the mode of knowing more deeply those same things known (by the first path). The faculty of one endowed with final knowledge (aññātāvindriya) is the faculty arisen in regard to those things fully known at the fruit of arahantship.

1"Tīṇimāni, bhikkhave, indriyāni. Katamāni tīṇi? Anaññātaññassāmītindriyaṁ, aññindriyaṁ, aññātāvindriyaṁ – imāni kho, bhikkhave, tīṇi indriyānī"ti.

Tatiyaṁ.