At one time Venerable Anuruddha was staying near Sāvatthī on the bank of the Sutanu. Then several mendicants went up to Venerable Anuruddha, and exchanged greetings with him. When the greetings and polite conversation were over, they sat down to one side, and said to him:
“What things has Venerable Anuruddha developed and cultivated to attain great direct knowledge?”
“Reverends, I attained great direct knowledge by developing and cultivating the four kinds of mindfulness meditation. What four? I meditate observing an aspect of the body—keen, aware, and mindful, rid of covetousness and displeasure for the world. I meditate observing an aspect of feelings … mind … principles—keen, aware, and mindful, rid of covetousness and displeasure for the world. I attained great direct knowledge by developing and cultivating these four kinds of mindfulness meditation.
And it was by developing and cultivating these four kinds of mindfulness meditation that I directly knew the lower principle as lower, the middle principle as middle, and the higher principle as higher.”