“Nāvā Sutta: Discourse on the Ship“
“Suppose, monks a carpenter, or a carpenter’s apprentice has an axe and sees the marks of his fingers or the thumb on its handle. But, he will not know that so much of the handle had worn today, so much had worn yesterday, or so much had worn on the day before yesterday. But, he will still know from what is worn away that it has worn away.”
“In the same way, monks, when a monk engages himself in the development of the mind, he does not know, so much of the fermentations had worn today, so much had worn yesterday, or so much had worn on the day before yesterday. But, he will still know from what is worn away that they have worn away.”