If you would like some more detail of the history of the Proclamation head over to New Liturgical Movement.
Although calendars now give the date of Easter and the other feasts in the liturgical year for many years in advance, the Epiphany Proclamation still has value. it is a reminder of the centrality of the resurrection of the Lord in the liturgical year and the importance of the great mysteries of faith which are celebrated each year. This beautiful proclamation puts everything into perspective. Every liturgical celebration of the Church finds its authentic meaning in the Paschal Mystery, even Christmas. The Paschal Mystery was precisely why the Eternal Son of the Father, the Eternal Word, deigned to leap down from heaven and become incarnate in the womb of the Blessed Virgin Mary. He was born in time so that He could give His flesh for the life of the world.
Below is the Proclamation with the dates for 2015 as per the Irish Liturgical Calendar.
that, as we have rejoiced at the Nativity of our Lord Jesus Christ,
so by leave of God's mercy
we announce to you also the joy of his Resurrection,
who is our Saviour.
On the eighteenth day of February will fall Ash Wednesday, and the beginning of the fast of the most sacred Lenten season.
On the fifth day of April you will celebrate with joy Easter Day, the Paschal feast of our Lord Jesus Christ.
On the seventeenth day of May will be the Ascension of our Lord Jesus Christ.
On the twenty-fourth day of May, the feast of Pentecost.
On the seventh day of June, the feast of the Most Holy Body and Blood of Christ.
On the twenty-ninth day of November, the First Sunday of the Advent of our Lord Jesus Christ,
to whom is honor and glory for ever and ever.