This week in the traditional Roman Rite, we have one of its most ancient celebrations, the Ember Days. The Wednesday, Friday and Saturday of the first week of Lent are one of the four times during the liturgical year (hence the Latin title Quattuor Temporum) specially set apart by the Church for fasting and abstinence, as well as prayer for farming and harvests. The Ember Days also have a traditional association with the conferral of Holy Orders. Their antiquity is attested by Pope St Leo the Great in, among other places, one of his Pentecost sermons:
To the present solemnity, dearly beloved, we must also add that devotion, so that we might celebrate with holy observance the fast which conforms to the apostolic tradition. This ought to be numbered among the great gifts of the Holy Spirit, that, against the desires of the flesh and the snares of the devil, the protection of the fasts has been set up for us. By these we may overcome all temptations with the help of God. Let us fast on Wednesday and Friday. On Saturday, however, let us celebrate the vigil with the blessed apostle Peter as advocate for our prayers, that we might deserve to obtain the mercy of God in all things through our Lord Jesus Christ, who lives and reigns with the Father and with the Holy Spirit for ever and ever. Amen. (Sermon 76)