Tear Out The Evil By The Root

"But perhaps thou sayest, I am a believer, and lust does not gain the ascendant over me, even if I think upon it frequently. Knowest thou not that a root breaks even a rock by long persistence? Admit not the seed, since it will rend thy faith asunder: tear out the evil by the root before it blossom, lest from being careless at the beginning thou have afterwards to seek for axes and fire. When thine eyes begin to be diseased, get them cured in good time, lest thou become blind, and then have to seek the physician." (Cyril of Jerusalem, Catechetical Lectures, 2:3)