"Monks, I have known two qualities through experience: discontent with regard to skillful qualities1 and unrelenting exertion. Relentlessly I exerted myself, [thinking,] 'Gladly would I let the flesh & blood in my body dry up, leaving just the skin, tendons, & bones, but if I have not attained what can be reached through human firmness, human persistence, human striving, there will be no relaxing my persistence.' From this heedfulness of mine was attained Awakening. From this heedfulness of mine was attained the unexcelled freedom from bondage.

"You, too, monks, should relentlessly exert yourselves, [thinking,] 'Gladly would we let the flesh & blood in our bodies dry up, leaving just the skin, tendons, & bones, but if we have not attained what can be reached through human firmness, human persistence, human striving, there will be no relaxing our persistence.' You, too, in no long time will reach & remain in the supreme goal of the holy life for which clansmen rightly go forth from home into homelessness, knowing & realizing it for yourselves in the here & now.

"Thus you should train yourselves: 'We will relentlessly exert ourselves, [thinking,] "Gladly would we let the flesh & blood in our bodies dry up, leaving just the skin, tendons, & bones, but if we have not attained what can be reached through human firmness, human persistence, human striving, there will be no relaxing our persistence."' That's how you should train yourselves."

Note

1. In other words, not allowing oneself to rest content merely with the skillful qualities developed on the path. In the Buddha's biography, this point is illustrated by his refusal to rest content with the formless absorptions he mastered under his first two teachers. See MN 36.