4 My sister's conversion is the fruit of the efforts of the saintly Julian. He has planted, it is for you to water, and the Lord will give the increase. Jesus Christ has given her to me to console me for the wound which the devil has inflicted on her. He has restored her from death to life. But in the words of the pagan poet, for her
There is no safety that I do not fear.
You know yourselves how slippery is the path of youth— a path on which I have myself fallen, and which you are now traversing not without fear. She, as she enters upon it, must have the advice and the encouragement of all, she must be aided by frequent letters from you, my reverend brothers. And— for “charity endures all things,” — I beg you to get from Pope Valerian a letter to confirm her resolution. A girl's courage, as you know, is strengthened when she realizes that persons in high place are interested in her.
Source: Letters (New Advent)