John of Kronstadt

How many have suffered and still suffer because their hearts were not firm in their good inclinations, because they imprudently looked with impure eyes, because they heard with ears unaccustomed to discern between good and evil, because they tasted greedily! The senses of the sin-loving, greedy flesh, unrestrained by reason and by God’s commandments, have drawn them into various worldly passions, have darkened their minds and hearts, deprived them of peace of heart, and taken away their free-will, making them the slaves of these senses. Thus you see how necessary it is to look, listen, taste, smell, and feel prudently; or, rather, how necessary it is to guard your heart so that through your outward senses, as through a window, no sin may steal in, and that the author himself of sin – the Devil – may not darken and wound that heavenly fledgling, our soul, with his poisonous and deathly arrows.