Sermon of Saint Leo
The observance of temperance is assigned especially to the Ember season that we may learn, as these seasons return in the course of years, how unceasingly we need to be purified. So long as we are tossed in the changes of this life we need, by fasting and alms-giving, to be cleansed from the stain of sins we have contracted through the frailty of our own flesh and our own concupiscence. Let us hunger a little, beloved; let us take a little from our habitual measure to help the poor.
Let the conscience of the generous be gladdened by the fruits of his liberality. When you give joy, you receive joy from the giving. The love of neighbor is also the love of God. Jesus declared that in the unity of this two-fold charity lies the fulfillment of the law and the prophets. Nor should any man doubt what he gives to a man he offers to God. We love the saying of our Lord and Saviour when He spoke of feeding and helping the poor. Whatsoever you have done, He said, to anyone of them you have done to Me. Therefore let us fast on Wednesday and Friday. On Saturday let us celebrate the Vigil at the shrine of Blessed Peter the Apostle, by whose merits and prayers we shall be helped to please by our fast and prayer, our merciful God.
The main thing in fasting is not that the body be deprived of food, but that the mind at the same time be withdrawn from wickedness, we should endeavor during Lent, not only to be temperate in eating and drinking, but especially to lead a modest life, sanctifying the days by persevering prayer and devoutly attending church., teaches Saint Leo. 
