From a sermon by St. Peter Chrysologus, 380-450 AD
“There are three things, my brethren, by which faith stands firm, devotion remains constant, and virtue endures. They are prayer, fasting and almsgiving. Prayer knocks at the door, fasting obtains, mercy receives. Prayer, mercy and fasting: these three are one, and they give life to each other.
“Fasting is the soul of prayer, almsgiving is the lifeblood of fasting. Let no one try to separate them; they cannot be separated. If you have only one of them or not all together, you have nothing. So if you pray, fast; if you fast, show mercy; if you want your petition to be heard, hear the petition of others. If you do not close your ear to others you open God’s ear to yourself.
“When you fast, see the fasting of others. If you want God to know that you are hungry, know that another is hungry. If you hope for mercy, show mercy. If you look for kindness, show kindness. If you want to receive, give. If you ask for yourself what you deny to others, your asking is a mockery.
“Let this be the pattern for all men when they practice mercy: show mercy to others in the same way, with the same generosity, with the same promptness, as you want others to show mercy to you. Therefore, let prayer, mercy and fasting be one single plea to God on our behalf, one speech in our defense, a threefold united prayer in our favor.”