"Bhikkhus, you should train thus: 'We will guard the doors of our sense faculties. On seeing a form with the eye, we will not grasp at its signs and features. Since, if we left the eye faculty unguarded, evil unwholesome states of covetousness and grief might invade us, we will practice the way of its restraint, we will guard the eye faculty, we will undertake the restraint of the eye faculty.'"