[At Saavatthii a certain monk said to the Ven. Saariputta:]
"Friend, Saariputta, my companion has renounced the training and reverted to the lower life."
"This is what happens, friend, with one whose sense-doors are unguarded, who is immoderate in eating and not given to wakefulness [like that monk]. As long as he lives it will be impossible for him to maintain the holy life in all its fullness and purity. But if a monk guards his sense-doors, is moderate in eating and given to watchfulness, then it will be possible for him, as long as he lives, to maintain the holy life in all its fullness and purity.
"And how, friend, does one guard the sense-doors? In this a monk seeing an object with the eye, does not seize hold of either its general appearance or its details. Because anyone dwelling with the eye-faculty uncontrolled could be overwhelmed by cupidity and dejection, evil and unwholesome states of mind, therefore he practices to control the eye-faculty, guards it and gains control over it. So one guards the sense-doors.
[Similarly with ear, nose, tongue, body (touch), mind]
"And how, friend, is one moderate in eating? In this a monk takes his food properly considering, not for sport, for intoxication, for adornment or beautification, but purely for the maintenance and nourishment of this body, for keeping it unharmed, as an aid to the practice of the holy life, thinking: 'I shall put an end to the old feeling, and not produce any new feeling. Thus I shall keep going, incur no fault, and live at ease.' That, friend, is how one is moderate in eating.
"And how, friend, is one given to watchfulness? In this a monk walks up and down by day and then sits, thus cleansing his mind from obstructive states. [Similarly for the first watch of the night.] In the middle watch of the night, lying on his right side, he adopts the lion posture, resting one foot on the other, mindful and clearly aware, with his thoughts fixed on rising. In the last watch of the night he rises, walks up and down, and then sits, thus cleansing his mind from obstructive states. That, friend, is how one is given to watchfulness.
"Therefore, this is how you should train yourselves: 'We will guard the doors of our senses, be moderate in eating and given to watchfulness.'
"This, friend, is the way for you to train yourself."