13 Avoid the company of young men. Let long baited youths dandified and wanton never be seen under your roof. Repel a singer as you would some bane. Hurry from your house women who live by playing and singing, the devil's choir whose songs are the fatal ones of sirens. Do not arrogate to yourself a widow's license and appear in public preceded by a host of eunuchs. It is a most mischievous thing for those who are weak owing to their sex and youth to misuse their own discretion and to suppose that things are lawful because they are pleasant.
“All things are lawful, but all things are not expedient.” No frizzled steward nor shapely foster brother nor fair and ruddy footman must dangle at your heels. Sometimes the tone of the mistress is inferred from the dress of the maid. Seek the society of holy virgins and widows; and, if need arises for holding converse with men, do not shun having witnesses, and let your conversation be marked with such confidence that the entry of a third person shall neither startle you nor make you blush.
The face is the mirror of the mind and a woman's eyes without a word betray the secrets of her heart. I have lately seen a most miserable scandal traverse the entire East. The lady's age and style, her dress and mien, the indiscriminate company she kept, her dainty table and her regal appointments bespoke her the bride of a Nero or of a Sardanapallus. The scars of others should teach us caution. 'When he that causes trouble is scourged the fool will be wiser.' A holy love knows no impatience.
A false rumor is quickly crushed and the after life passes judgment on that which has gone before. It is not indeed possible that any one should come to the end of life's race without suffering from calumny; the wicked find it a consolation to carp at the good, supposing the guilt of sin to be less, in proportion as the number of those who commit it is greater. Still a fire of straw quickly dies out and a spreading flame soon expires if fuel to it be wanting. Whether the report which prevailed a year ago was true or false, when once the sin ceases, the scandal also will cease.
I do not say this because I fear anything wrong in your case but because, owing to my deep affection for you, there is no safety that I do not fear. Oh! That you could see your sister and that it might be yours to hear the eloquence of her holy lips and to behold the mighty spirit which animates her diminutive frame. You might hear the whole contents of the old and new testaments come bubbling up out of her heart. Fasting is her sport, and prayer she makes her pastime. Like Miriam after the drowning Pharaoh she takes up her timbrel and sings to the virgin choir, “Let us sing to the Lord for He has triumphed gloriously; the horse and his rider has he thrown into the sea.” She teaches her companions to be music girls but music girls for Christ, to be luteplayers but luteplayers for the Saviour.
In this occupation she passes both day and night and with oil ready to put in the lamps she waits the coming of the Bridegroom. Do you therefore imitate your kinswoman. Let Rome have in you what a grander city than Rome, I mean Bethlehem, has in her.
Source: Letters (New Advent)