Every Sacrament is a sharing in the Life, Death and Resurrection of Christ.
And what is the Life, Death and Resurrection of Christ, but the Paschal Mystery?
To prepare for this Paschal Mystery participation, we have to LIVE the faith of our ancestors: the Hebrews - longing for the Savior. Preparing to receive Him by listening to the words of the Prophets.
The people who walked in darkness have seen a Great Light.
The Hebrews had many dark times in their history; we too have dark times in our lives. There is always hope: the Light of Christ.
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As we spend this Advent preparing for the SECOND coming of the Lord, we can see in the prophecies clues to His first coming as well as clues to His second coming. We can see both the messianic message - and the moral message: how to prepare our hearts to receive Him, both in the sacraments and when He comes at Parousia.