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Today, 29 September, is the celebration of the Feast Day of St. Michael and All Angels (although Father Acker and I celebrated it yesterday at our Friday Morning Prayer and Healing Service with Holy Communion). This was a feast that I was not terribly familiar with, so I was glad to read an informative explanation in the "Saint of the Day" e-mail from AmericanCatholic.org:
Angels—messengers from God—appear frequently in Scripture, but only Michael, Gabriel, and Raphael are named.
Michael appears in Daniel's vision as "the great prince" who defends Israel against its enemies; in the Book of Revelation, he leads God's armies to final victory over the forces of evil. Devotion to Michael is the oldest angelic devotion, rising in the East in the fourth century. The Church in the West began to observe a feast honoring Michael and the angels in the fifth century.
Gabriel also makes an appearance in Daniel's visions, announcing Michael's role in God's plan. His best-known appearance is an encounter with a young Jewish girl named Mary, who consents to bear the Messiah.
Raphael's activity is confined to the Old Testament story of Tobit. There he appears to guide Tobit's son Tobiah through a series of fantastic adventures which lead to a threefold happy ending: Tobiah's marriage to Sarah, the healing of Tobit's blindness and the restoration of the family fortune.
The memorials of Gabriel (March 24) and Raphael (October 24) were added to the Roman calendar in 1921. The 1970 revision of the calendar joined their feasts to Michael's.
Each of these archangels performs a different mission in Scripture: Michael protects; Gabriel announces; Raphael guides. Earlier belief that inexplicable events were due to the actions of spiritual beings has given way to a scientific world-view and a different sense of cause and effect. Yet believers still experience God's protection, communication and guidance in ways which defy description. We cannot dismiss angels too lightly.
As I've read much British literature over the years (mostly in graduate school but also for my own enjoyment), I have come across the term "Michaelmas" as a British holiday (along with "Candlemas" which occurs on 2 February) and never knew what it celebrated; I only knew it occurred sometime in autumn. So for my own edification and perhaps for yours as well, I discovered an article about Michaelmas from the Historic-UK Web site (read the complete entry here: Michaelmas):
Michaelmas, or the Feast of Michael and All Angels, is celebrated on the 29th of September every year. As it falls near the equinox, the day is associated with the beginning of autumn and the shortening of days; in England, it is one of the “quarter days”.
There are traditionally four “quarter days” in a year (Lady Day (25th March), Midsummer (24th June), Michaelmas (29th September) and Christmas (25th December)). They are spaced three months apart, on religious festivals, usually close to the solstices or equinoxes. They were the four dates on which servants were hired, rents due or leases begun. It used to be said that harvest had to be completed by Michaelmas, almost like the marking of the end of the productive season and the beginning of the new cycle of farming. It was the time at which new servants were hired or land was exchanged and debts were paid. This is how it came to be for Michaelmas to be the time for electing magistrates and also the beginning of legal and university terms.
St Michael is one of the principal angelic warriors, protector against the dark of the night and the Archangel who fought against Satan and his evil angels. As Michaelmas is the time that the darker nights and colder days begin - the edge into winter - the celebration of Michaelmas is associated with encouraging protection during these dark months. It was believed that negative forces were stronger in darkness and so families would require stronger defences during the later months of the year.
The Scripture readings for Morning Prayer included Revelation 12:7-12 regarding Michael the Archangel and the War in Heaven:
7 Now war arose in heaven, Michael and his angels fighting against the dragon. And the dragon and his angels fought back, 8 but he was defeated, and there was no longer any place for them in heaven. 9 And the great dragon was thrown down, that ancient serpent, who is called the devil and Satan, the deceiver of the whole world—he was thrown down to the earth, and his angels were thrown down with him. 10 And I heard a loud voice in heaven, saying, “Now the salvation and the power and the kingdom of our God and the authority of his Christ have come, for the accuser of our brothers  has been thrown down, who accuses them day and night before our God. 11 And they have conquered him by the blood of the Lamb and by the word of their testimony, for they loved not their lives even unto death. 12 Therefore, rejoice, O heavens and you who dwell in them! But woe to you, O earth and sea, for the devil has come down to you in great wrath, because he knows that his time is short!”
(English Standard Version)
In the 1928 Book of Common Prayer, the Book of Common Prayer 2011, and in The Divine Hours series edited by Phyllis Tickle, I found several Collects to pray on Michaelmas, and I liked this one the best -- from Divine Hours: Prayers for Summertime, Midday Prayer for Monday nearest September 28:
Everlasting God, you have ordained and constituted the ministries of the angels and men in a wonderful order. Mercifully grant now that, as your holy angels always serve and worship you in heaven, so by your appointment they may help and defend us on earth; through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, for ever and ever. Amen.
The Christian season of Michaelmas lasts from 29 September all the way to the beginning of Advent, so we have much time to pray this song during Morning Prayer, immediately following the First Reading of Holy Scripture in the Book of Common Prayer 2011:
The Angels' Song of the Lamb (Magna et mirabilia):
Great and amazing are your deeds,
O Lord God the Almighty.
Just and true are your ways,
O King of the nations.
Who will not fear, O Lord, and glorify your Name?
For you alone are holy.
All nations will come and worship you,
for your righteous acts have been revealed. (Revelation 15.3-4)
So there -- we have the historical and spiritual background of Michaelmas as well as Scripture and prayer with which to celebrate this day and season, remembering that although Angels are both wonderful in their beauty and terrible in their fury, they are created beings, made by the King of kings and the Lord of lords for His purposes and for our help. We humans, formed in the likeness of God, were created but "a little lower than the angels, crowned with glory and honor" (Psalm 8:5), made by the Magnificent One, the Lord God of Hosts.