“When a person yields to fantasies and is overcome by sinful thoughts, it is from there, from the imagination, that all evil comes! And when he has suffered many spiritual shipwrecks mentally and has been wounded repeatedly by hedonistic fantasies, then as soon as Satan comes back again with similar fantasies and shows them to the mind, immediately the person is captured. This is why one must not yield to them, so that the passions and fantasies do not become firm and strong. Keep the eyes of your soul wide open; guard your senses, both those of the body (primarily the eyes) as well as those of the soul (especially by keeping the mind from wandering). This is necessary because it is through these senses that all the poisonous germs of spiritual diseases creep in. And thus, in time, the careless Christian contracts many diseases and loses the invaluable health of his immortal soul. Adultery of the soul occurs very easily when we allow filthy thoughts with their corresponding fantasies within us to overcome us. My child, be careful with your eyes if you want to conquer the demon of lust. Likewise, it is no less dangerous to look at indecent images, newspapers, magazines, etc.”

–  ‘Counsels from the Holy Mountain’