[607] "Guarded as to the doors of the faculties (indriyesu guttadvāro)": there is the state of being guarded as to the doors of the faculties; there is the state of being unguarded as to the doors of the faculties.
Therein, which is the state of being unguarded as to the doors of the faculties? Here someone, having seen a form (rūpa) with the eye, is one who grasps at the sign (nimitta), one who grasps at the secondary features (anubyañjana); since, while he dwells with the eye faculty unrestrained, evil unwholesome phenomena (dhammā) of covetousness and grief (abhijjhā-domanassa) might flow in upon him, he does not practice for its restraint, he does not guard the eye faculty, he does not undertake restraint of the eye faculty. Having heard a sound with the ear … having smelt an odor with the nose … having tasted a flavor with the tongue … having touched a tangible object (phoṭṭhabba) with the body … having cognized a mental phenomenon (dhamma) with the mind (mano), he is one who grasps at the sign, one who grasps at the secondary features; since, while he dwells with the mind faculty unrestrained, evil unwholesome phenomena of covetousness and grief might flow in upon him, he does not practice for its restraint, he does not guard the mind faculty, he does not undertake restraint of the mind faculty. That which is the absence of guarding, the absence of protecting, the absence of watchfulness, the absence of restraint with regard to these six faculties — this is called the state of being unguarded as to the doors of the faculties.
Therein, which is the state of being guarded as to the doors of the faculties? Here someone, having seen a form with the eye, is not one who grasps at the sign, not one who grasps at the secondary features; since, while he dwells with the eye faculty unrestrained, evil unwholesome phenomena of covetousness and grief might flow in upon him, he practices for its restraint, he guards the eye faculty, he undertakes restraint of the eye faculty. Having heard a sound with the ear … having smelt an odor with the nose … having tasted a flavor with the tongue … having touched a tangible object with the body … having cognized a mental phenomenon with the mind, he is not one who grasps at the sign, not one who grasps at the secondary features; since, while he dwells with the mind faculty unrestrained, evil unwholesome phenomena of covetousness and grief might flow in upon him, he practices for its restraint, he guards the mind faculty, he undertakes restraint of the mind faculty. That which is the guarding, the protecting, the watchfulness, the restraint with regard to these six faculties — this is called the state of being guarded as to the doors of the faculties.
He is endowed with … possessed of this state of being guarded as to the doors of the faculties; therefore he is called "guarded as to the doors of the faculties."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.