The following was written for religious, but lay people can learn much from The True Spouse of Jesus Christ by St. Alphonsus Maria de Liguori.  The following excerpt is also found at www.saintsworks.net.

‘Turn away your eyes lest they behold vanity; (cf. Ps. 119:37) for license causes souls to perish.’—St. Poemen

Almost all our rebellious passions spring from unguarded looks; for, generally speaking, it is by the sight that all inordinate affections and desires are excited.

Hence, holy Job made a covenant with his eyes, that he would not so much as think upon a virgin.

Why did he say that he would not so much as think upon a virgin? Should he not have said that he made a covenant with his eyes not to look at a virgin? No; he very properly said that he would not think upon a virgin; because thoughts are so connected with looks, that the former cannot be separated from the latter, and therefore, to escape the molestation of evil imaginations, he resolved never to fix his eyes on a woman.

St. Augustine says: “The thought follows the look; delight comes after the thought; and consent after delight.” From the look proceeds the thought; from the thought the desire; for, as St. Francis de Sales says, “what is not seen is not desired, and to the desire succeeds the consent.”

If Eve had not looked at the forbidden apple, she should not have fallen; but because she saw that it was good to eat, and fair to the eyes, and beautiful to behold, she took of the fruit thereof, and did eat.

The devil first tempts us to look, then to desire, and afterwards to consent.

St. Jerome says that Satan requires “only a beginning on our part.” If we begin, he will complete our destruction.

A deliberate glance at a person of a different sex often enkindles an infernal spark, which consumes the soul. “Through the eyes,” says St. Bernard, “the deadly arrows of love enter.” The first dart that wounds and frequently robs chaste souls of life finds admission through the eyes. By them David, the beloved of God, fell. By them was Solomon, once the inspired of the Holy Ghost, drawn into the greatest abominations. Oh! how many are lost by indulging their sight!

The eyes must be carefully guarded by all who expect not to be obliged to join in the lamentation of Jeremiah: “My eye hath wasted my soul.” By the introduction of sinful affections my eyes have destroyed my soul. Hence St. Gregory says, that “the eyes, because they draw us to sin, must be depressed.”

If not restrained, they will become instruments of hell, to force the soul to sin almost against its will.

“He that looks at a dangerous object,” continues the saint, “begins to will what he wills not.” It was this the inspired writer intended to express when he said of Holofernes, that the beauty of Judith made his soul captive.

Seneca says that “blindness is a part of innocence.” And Tertullian relates that a certain pagan philosopher, to free himself from impurity, plucked out his eyes. Such an act would be unlawful in us: but he that desires to preserve chastity must avoid the sight of objects that are apt to excite unchaste thoughts. “Gaze not about,” says the Holy Ghost, “upon another’s beauty; . . . hereby lust is enkindled as a fire.” Gaze not upon another’s beauty; for from looks arise evil imaginations, by which an impure fire is lighted up.

Hence St. Francis de Sales used to say, that “they who wish to exclude an enemy from the city must keep the gates locked.”

Hence, to avoid the sight of dangerous objects, the saints were accustomed to keep their eyes almost continually fixed on the earth, and to abstain even from looking at innocent objects.

After being a novice for a year, St. Bernard could not tell whether his cell was vaulted. In consequence of never raising his eyes from the ground, he never knew that there were but three windows to the church of the monastery, in which he spent his novitiate.

He once, without perceiving a lake, walked along its banks for nearly an entire day; and hearing his companions speak about it, he asked when they had seen it.

St. Peter of Alcantara kept his eyes constantly cast down, so that he did not know the brothers with whom he conversed. It was by the voice, and not by the countenance, that he was able to recognize them.

The saints were particularly cautious not to look at persons of a different sex.

St. Hugh, bishop, when compelled to speak with women, never looked at them in the face.

St. Clare would never fix her eyes on the face of a man. She was greatly afflicted because, when raising her eyes at the elevation to see the consecrated host, she once involuntarily saw the countenance of the priest.

St. Aloysius never looked at his own mother in the face.

It is related of St. Arsenius, that a noble lady went to visit him in the desert, to beg of him to recommend her to God. When the saint perceived that his visitor was a woman, he turned away from her, she then said to him: “Arsenius, since you will neither see or hear me, at least remember me in your prayers.” “No,” replied the saint, “but I will beg of God to make me forget you, and never more to think of you.”

From these examples may be seen the folly and temerity of some religious who, though they have not the sanctity of a St. Clare, still gaze around from the terrace, in the parlor, and in the church, upon every object that presents itself, even on persons of a different sex. And notwithstanding their unguarded looks, they expect to be free from temptations and from the danger of sin.

For having once looked deliberately at a woman who was gathering ears of corn, the Abbot Pastor was tormented for forty years by temptations against chastity.

St. Gregory states that the temptation, to conquer which St. Benedict rolled himself in thorns, arose from one incautious glance at a woman.

St. Jerome, though living in a cave at Bethlehem, in continual prayer and macerations of the flesh, was terribly molested by the remembrance of ladies whom he had long before seen in Rome. Why should not similar molestations be the lot of the religious who wilfully and without reserve fixes her eyes on persons of a different sex?

“It is not,” says St. Francis de Sales, “the seeing of objects so much as the fixing of our eyes upon them that proves most pernicious.” “If,” says St. Augustine, “our eyes should by chance fall upon others, let us take care never to fix them upon any one.” Father Manareo, when taking leave of St. Ignatius for a distant place, looked steadfastly in his face: for this look he was corrected by the saint.

From the conduct of St. Ignatius on this occasion, we learn that it was not becoming in religious to fix their eyes on the countenance of a person even of the same sex, particularly if the person is young. But I do not see how looks at young persons of a different sex can be excused from the guilt of a venial fault, or even from mortal sin, when there is proximate danger of criminal consent. “It is not lawful,” says St. Gregory, “to behold what it is not lawful to covet.”

The evil thought that proceeds from looks, though it should be rejected, never fails to leave a stain upon the soul. Brother Roger, a Franciscan of singular purity, being once asked why he was so reserved in his interaction with women, replied, that when men avoid the occasions of sin, God preserves them; but when they expose themselves to danger, they are justly abandoned by the Lord, and easily fall into some grievous transgressions.

The indulgence of the eyes, if not productive of any other evil, at least destroys recollection during the time of prayer. For, the images and impressions caused by the objects seen before, or by the wandering of the eyes, during prayer, will occasion a thousand distractions, and banish all recollection from the soul. It is certain that without recollection a religious can pay but little attention to the practice of humility, patience, mortification, or of the other virtues. Hence it is her duty to abstain from all looks of curiosity, which distract her mind from holy thoughts. Let her eyes be directed only to objects which raise the soul to God.

St. Bernard used to say, that to fix the eyes upon the earth contributes to keep the heart in heaven. “Where,” says St. Gregory, “Christ is, there modesty is found.” Wherever Jesus Christ dwells by love, there modesty is practised.

However, I do not mean to say that the eyes should never be raised or never fixed on any object. No; but they ought to be directed only to what inspires devotion, to sacred images, and to the beauty of creation, which elevate the soul to the contemplation of the divinity. Except in looking at such objects, a religious should in general keep the eyes cast down, and particulary in places where they may fall upon dangerous objects. In conversing with men, she should never shift the eyes about to look at them, and much less to look at them a second time.

To practise modesty of the eyes is the duty of a religious, not only because it is necessary for her own improvement in virtue, but also because it is necessary for the edification of others.

God only knows the human heart: man sees only the exterior actions, and by them he is edified or scandalized. “A man,” says the Holy Ghost, “is known by his look.” By the countenance the interior is known. Hence, like St. John the Baptist, a religious should be a burning and shining light. She ought to be a torch burning with charity, and shining resplendent by her modesty, to all who behold her. To religious the following words of the Apostle are particularly applicable: “We are made a spectacle to the world, and to angels, and to men.” And again: “Let your modesty be known to all men: the Lord is nigh.” Religious are attentively observed by the angels and by men; and therefore their modesty should be made manifest before all; if they do not practise modesty, terrible shall be the account which they must render to God on the day of judgment. Oh! what devotion does a modest religious inspire, what edification does she give, by keeping her eyes always cast down!

St. Francis of Assisi once said to his companion, that he was going out to preach. After walking through the town, with his eyes fixed on the ground, he returned to the convent. His companion asked him when he would preach the sermon. We have, replied the saint, by the modesty of our looks, given an excellent instruction to all who saw us.

It is related of St. Aloysius, that when he walked through Rome the students would stand in the streets to observe and admire his great modesty.

St. Ambrose says, that to men of the world the modesty of the saints is a powerful exhortation to amendment of life.

“The look of a just man is an admonition to many.” The saint adds: “How delightful it is to do good to others by your appearance!”

It is related of St. Bernardine of Sienna, that even when a secular, his presence was sufficient to restrain the licentiousness of his young companions, who, as soon as they saw him, were accustomed to give to one another notice that he was coming. On his arrival they became silent or changed the subject of their conversation. It is also related of St. Gregory of Nyssa, and of St. Ephrem, that their very appearance inspired piety, and that the sanctity and modesty of their exterior edified and improved all that beheld them.

When Innocent II visited St. Bernard at Clairvaux, such was the exterior modesty of the saint and of his monks, that the Pope and his cardinals were moved to tears of devotion. Surius relates a very extraordinary fact of St. Lucian, a monk and martyr. By his modesty he induced so many pagans to embrace the faith, that the Emperor Maximian fearing that he should be converted to Christianity by the appearance of the saint, would not allow the holy man to be brought within his view, but spoke to him from behind a screen.

That our Redeemer was the first who taught, by his example, modesty of the eyes, may, as a learned author remarks, be inferred from the holy evangelists, who say that on some occasion he raised his eyes. “And he, lifting up his eyes on his disciples. When Jesus therefore had lifted up his eyes.” From these passages we may conclude that the Redeemer ordinarily kept his eyes cast down.

Hence the Apostle, praising the modesty of the Saviour, says: “I beseech you, by the mildness and modesty of Christ.”

I shall conclude this subject with what St. Basil said to his monks: “If, my children, we desire to raise the soul towards heaven, let us direct the eyes towards the earth.”

From the moment we awake in the morning, let us pray continually in the words of holy David: “Turn away my eyes, that they may not behold vanity.”