How so? It’s when a mendicant develops the basis of psychic power that has immersion due to enthusiasm, and active effort. They think: ‘My enthusiasm won’t be too lax or too tense. And it’ll be neither constricted internally nor scattered externally.’ And they meditate perceiving before and behind: as before, so behind; as behind, so before; as below, so above; as above, so below; as by day, so by night; as by night, so by day. And so, with an open and unenveloped heart, they develop a mind that’s full of radiance. They develop the basis of psychic power that has immersion due to energy … mental development … inquiry, and active effort. They think: ‘My inquiry won’t be too lax or too tense. And it’ll be neither constricted internally nor scattered externally.’ And they meditate perceiving before and behind: as before, so behind; as behind, so before; as below, so above; as above, so below; as by day, so by night; as by night, so by day. And so, with an open and unenveloped heart, they develop a mind that’s full of radiance.

And what is enthusiasm that’s too lax? It’s when enthusiasm is coupled with laziness. This is called lax enthusiasm.

And what is enthusiasm that’s too tense? It’s when enthusiasm is coupled with restlessness. This is called tense enthusiasm.