Four times a year, the Church sets aside three days to "thank God for the gifts of nature and to teach us to make use of them in moderation" through fasting and prayer. These quarterly periods take place around the beginnings of the four natural seasons. The Ember Days were prescribed for the entire Church by Pope Gregory VII (1073-1085). "Ember" comes from the Latin word "tempora," meaning "seasons."
These days are four series of Wednesdays, Fridays, and Saturdays which correspond to the natural seasons of the year. Autumn brings "Michaelmas Embertide" after the Feast of the Exaltation of the Holy Cross; Winter, the Advent Embertide after the Feast of St. Lucy; Spring, the Lenten Embertide, the week after Ash Wednesday; and Summer, the Whit Embertide after Pentecost Sunday.
Although Ember Days are no longer required in Roman Catholicism following Vatican II, they can still be observed by the Faithful. On Wednesday and Saturday the abstinence is only partial, meaning meat may be eaten at the main meal, although ever since reading about the Sabbatine Priviledge I stopped eating meat on Wednesdays, Fridays and Saturdays. Ember Fridays are just like Good Friday, fast and abstinence from all meat. Ember Days are days favored for priestly ordinations, prayer for priests, first Communions, almsgiving and other penitential and charitable acts, and prayer for the souls in Purgatory.
We offer our fast and abstinence for the sanctification of the clergy, as traditionally ordinations are held on Ember Saturdays. The Ember Days retain the ancient tradition from the very beginnings of the Church of Wednesday and Friday as days of penitential fasting. Today would be a good day to begin a novena for all priests. Here is a prayer we say for our priests every day:
O God, Who hast appointed Thine only-begotten Son to be the eternal High Priest for the glory of Thy Majesty and the salvation of mankind; grant that they whom He hath chosen to be His ministers and the stewards of His Mysteries, may be found faithful in the fulfillment of the ministry which they have received. Through the same Christ our Lord. Amen.
Tertullian and other early writers speak of the ordinary fasts of rule practiced by the first Christians on all Wednesdays and Fridays of the year outside of Paschal time. Around 450 Pope St. Leo the Great wrote of the Ember Days in a series of sermons:
By voluntary mortifications the flesh dies to its
concupiscences, and the spirit is renewed in virtue. But
since fasting alone is not sufficient whereby to secure the
soul’s salvation, let us add to it works of mercy to the poor.