While a mendicant is meditating—diligent, keen, and resolute—the faculty of equanimity arises. They understand: ‘The faculty of equanimity has arisen in me. And that has a basis, a source, a condition, and a reason. It’s not possible that the faculty of equanimity will arise without a basis, a source, a condition, or a reason.’ They understand the faculty of equanimity, its origin, its cessation, and where that faculty of equanimity that’s arisen ceases without remainder. And where does that faculty of equanimity that’s arisen cease without remainder? It’s when a mendicant, going totally beyond the dimension of neither perception nor non-perception, enters and remains in the cessation of perception and feeling. That’s where the faculty of equanimity that’s arisen ceases without remainder. They’re called a mendicant who understands the cessation of the faculty of equanimity, and who applies their mind to that end.”

Linked Discourses 48.41 5. Old Age Old Age