Having summed up the address of Liberius, St. Ambrose passes on to the virtues of his sister, especially her fasts, which however he advises her to moderate to some extent, and to exercise herself in other matters, after the example which he adduces. Especially he recommends the Lord's Prayer, and the repetition of Psalms by night, and the recitation of the Creed before daylight.
15. After such a fashion did Liberius of holy memory address you, in words beyond the reality of practice in most cases, but coming short of your performance, who have not only attained to the whole of discipline by your virtue, but have surpassed it in your zeal. For we are bidden to practise fasting, but only for single days; but you, multiplying nights and days, pass untold periods without food, and if ever requested to partake of some, and to lay aside your book a little while, you at once answer: “Man does not live by bread alone, but by every word of God.” Your very meals consisted but of what food came to hand, so that fasting is to be preferred to eating what was repugnant; your drink is from the spring, your weeping and prayer combine, your sleep is on your book.
16. These kings were suited to younger years, while he was ripening with the gray hairs of age; but when a virgin has gained the triumph over her subdued body, she should lessen her toil, that she may be preserved as teacher for a younger age. The vine laden with the fruitful branches of full growth soon breaks unless it be from time to time kept back. But while it is young let it grow rank, and as it grows older be pruned, so as not to grow into a forest of twigs, or die deprived of life by its exceptive produce. A good husbandman by tending the soil keeps the vine in excellent order, protects it from cold, and guards it from being parched by the mid-day sun. And he works his land by turns, or if he will not let it lie fallow, he alternates his crops, so that the fields may rest through change of produce. Do you too, a veteran in virginity, at least sow the fields of your breast with different seeds, at one time with moderate sustenance, at another with sparing fasts, with reading, work, and prayer, that change of toil may be as a truce for rest.
17. The whole land does not produce the same harvest. On one side vines grow on the hills, on another you can see the purple olives, elsewhere the scented roses. And after leaving the plough, the strong husbandman with his fingers scrapes the soil to plant the roots of flowers, and with the rough hands wherewith he turns the bullocks striving among the vines, he gently presses the udders of the sheep. The land is the better the more numerous are its fruits. So do you, following the example of a good husbandman, avoid cleaving your soil with perpetual fastings as if with deep ploughings. Let the rose of modesty bloom in your garden, and the lily of the mind, and let the violet beds drink from the source of sacred blood. There is a common saying, “What you wish to perform abundantly, sometimes do not do at all.” There ought to be something to add to the days of Lent, but so that nothing be done for the sake of ostentation, but of religion.
18. Frequent prayer also commends us to God. For if the prophet says, “Seven times a day have I praised You,” though he was busy with the affairs of a kingdom, what ought we to do, who read: “Watch and pray that you enter not into temptation”? Certainly our customary prayers ought to be said with giving of thanks, when we rise from sleep, when we go forth, when we prepare to receive food, after receiving it, and at the hour of incense, when at last we are going to rest.
19. And again in your bed-chamber itself, I would have you join psalms in frequent interchange with the Lord's prayer, either when you wake up, or before sleep bedews your body, so that at the very commencement of rest sleep may find you free from the care of worldly matters, meditating upon the things of God. And, indeed, he who first found out the name of Philosophy itself, every day before he went to rest, had the flute-player play softer melodies to soothe his mind disturbed by worldly cares. But he, like a man washing tiles, fruitlessly desired to drive away worldly things by worldly means, for he was, indeed, rather besmearing himself with fresh mud, in seeking a reward from pleasure, but let us, having wiped off the filth of earthly vices, purify our utmost souls from every defilement of the flesh.
20. We ought, also, specially to repeat the Creed, as a seal upon our hearts, daily, before light, and to recur to it in thought whenever we are in fear of anything. For when is the soldier in his tent or the warrior in battle without his military oath?
Source: Concerning Virgins (New Advent)