§ 90. There are these five strengths. Which five? Strength of conviction, strength of persistence, strength of mindfulness, strength of concentration, & strength of discernment. These are the five strengths.

Just as the River Ganges flows to the east, slopes to the east, inclines to the east, in the same way when a monk develops & pursues the five strengths, he flows to Unbinding, slopes to Unbinding, inclines to Unbinding.

And how is it that when a monk develops & pursues the five strengths, he flows… slopes… inclines to Unbinding?

There is the case where the monk develops strength of conviction dependent on seclusion, dependent on dispassion, dependent on cessation, resulting in letting go. He develops strength of persistence… mindfulness… concentration… discernment dependent on seclusion… dispassion… cessation, resulting in letting go.

This is how a monk, when developing & pursuing the five strengths, flows… slopes… inclines to Unbinding.

SN 50:1

§ 91. There is a manner of reckoning whereby the five faculties are the same as the five strengths, and the five strengths the same as the five faculties. And what is that method?

Whatever is the faculty of conviction, that is the strength of conviction. Whatever is the strength of conviction, that is the faculty of conviction. Whatever is the faculty of persistence, that is the strength of persistence. Whatever is the strength of persistence, that is the faculty of persistence. Whatever is the faculty of mindfulness, that is the strength of mindfulness. Whatever is the strength of mindfulness, that is the faculty of mindfulness. Whatever is the faculty of concentration, that is the strength of concentration. Whatever is the strength of concentration, that is the faculty of concentration. Whatever is the faculty of discernment, that is the strength of discernment. Whatever is the strength of discernment, that is the faculty of discernment.

Imagine a river—flowing, sloping, inclining toward the east—in whose midst is an island. There is a manner of reckoning whereby the river is classified as one current, and another manner of reckoning whereby it is classified as two.

And what is the first manner of reckoning? Whatever water lies to the east of the island, and whatever water lies to the west. This is the manner of reckoning whereby the river is classified as one current.

And what is the second manner of reckoning? Whatever water lies to the north of the island, and whatever water lies to the south. This is the manner of reckoning whereby the river is classified as two.

In the same way, whatever is the faculty of conviction, that is the strength of conviction. Whatever is the strength of conviction, that is the faculty of conviction…. Whatever is the faculty of discernment, that is the strength of discernment. Whatever is the strength of discernment, that is the faculty of discernment.

SN 48:43