"She must offer God her body and chastity by means of a vow. After making her vow she no longer has the power to give up chastity without giving up her title to heaven. Hence she will watch over her vow so jealously that not for a single moment will she let the least thought of marriage enter her heart. In this way her holy vow will serve as a strong barrier between her soul and every project contrary to her resolution.
"A vow not only makes good works done as a result of it more acceptable to God but it also encourages us to put them into practice. It gives God not only the good works that are the fruits of our good will but likewise dedicates to him the will itself, the tree on which all our actions grow.
"By simple chastity we lend our body to God while still retaining the liberty to use it for sensual pleasure at some other time. By the vow of chastity we make him an absolute and irrevocable gift of our body without reserving to ourselves any power of recall. In this way we happily make ourselves slaves of him whose service is better than all royal power.
"Souls who are so happy as to desire to follow this advice should do so prudently, devoutly and firmly, having first examined their resolutions, invoked God’s divine inspiration, and taken counsel of a wise and devout director. Moreover, this renunciation must be made purely and simply with the single intention of turning all the affection of one’s soul toward God and uniting one’s heart wholly with that of his Divine Majesty.
"In God’s eyes nothing can truly merit praise except what is done for his sake."
(St. Francis de Sales, Introduction to the Devout Life, Third Part. No. 40)