“Look at dangerous objects”, says St. Francis De Sales, “is not so hurtful to us as to repeat the look”. And St. John Chrysostom adds, that “it is necessary to turn away the eyes whose dress or manner is immodest, but even from those whose demeanor is full of modesty”. Hence, holy Joe made a compact with his eyes not to look at any women, even at a chaste virgin because he knew from looks, evil thoughts arise. "I made a covenant with my eyes that I would not so much as think upon a virgin."

There are some more quotes here you might find worthwhile.