INVITATORY
The Invitatory is said when this is the first ‘hour’ of the day.
Lord, + open my lips.
— And my mouth will proclaim your praise.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
The antiphon is repeated. In individual recitation, the antiphon may be said only at the beginning of the psalm; it need not be repeated after each strophe.
Psalm 95
A call to praise God
Encourage each other daily while it is still today (Hebrews 3:13).
Come, let us sing to the Lord *
and shout with joy to the Rock who saves us.
Let us approach him with praise and thanksgiving *
and sing joyful songs to the Lord.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
The Lord is God, the mighty God, *
the great king over all the gods.
He holds in his hands the depths of the earth *
and the highest mountains as well.
He made the sea; it belongs to him, *
the dry land, too, for it was formed by his hands.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Come, then, let us bow down and worship, *
bending the knee before the Lord, our maker.
For he is our God and we are his people, *
the flock he shepherds.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Today, listen to the voice of the Lord: †
Do not grow stubborn, as your fathers did
in the wilderness, *
when at Meriba and Massah
they challenged me and provoked me, *
Although they had seen all of my works.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Forty years I endured that generation. *
I said, “They are a people whose hearts go astray
and they do not know my ways.”
So I swore in my anger, *
“They shall not enter into my rest.”
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Glory to the Father, and to the Son, *
and to the Holy Spirit:
as it was in the beginning, is now, *
and will be for ever. Amen.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
If the Invitatory is not said, then the following is used:
God, + come to my assistance.
— Lord, make haste to help me.
Glory to the Father, and to the Son, and to the Holy Spirit:
— as it was in the beginning, is now, and will be for ever. Amen. Alleluia.
HYMN
As John fulfilled his sacred charge,
Christ Jesus, Author of the world,
immersed this day in Jordan’s tide,
by bathing, washed its waters clean.
Born from the Virgin Mother’s womb,
he did not need to be baptized,
yet by his washing, he desired,
to take away our guilt and sin.
The Father speaks, his voice proclaims:
This is my own beloved Son;
from heaven’s height on him descends,
in dove-like form, the Spirit blest.
Beneath the myst’ry of this Name,
salvation shines within the Church;
the Trinity abides with her,
one God through every time and place.
All glory be to you, O Christ;
the Father and the Spirit blest,
in splendor from the heights of heav’n,
reveal that you are Life and Truth. Amen.
Tune: BRESLAU, 8 8 8 8
Music: first appeared in As Hymnodus Sacer, Leipzig 1625, adapted by Felix Mendelssohn Bartholdy, 1809-1847
or Mode I, melody 17; Liber Hymnarius, Solesmes, 1983*
Text: Implente munus debitum, ca. 10th c., © 2023 ICEL
PSALMODY
Ant. 1 The voice of the Lord, the God of majesty, echoes over the waters.
Psalm 29
A tribute of praise to the Word of God
The Father’s voice proclaimed: “This is my beloved Son” (Matthew 3:17).
O give the Lord, you sons of God, *
give the Lord glory and power;
give the Lord the glory of his name. *
Adore the Lord in his holy court.
The Lord’s voice resounding on the waters, *
the Lord on the immensity of waters;
the voice of the Lord, full of power, *
the voice of the Lord, full of splendor.
The Lord’s voice shattering the cedars, *
the Lord shatters the cedars of Lebanon;
he makes Lebanon leap like a calf *
and Sirion like a young wild-ox.
The Lord’s voice flashes flames of fire.
The Lord’s voice shaking the wilderness, *
the Lord shakes the wilderness of Kadesh;
the Lord’s voice rending the oak tree *
and stripping the forest bare.
The God of glory thunders. *
In his temple they all cry: “Glory!”
The Lord sat enthroned over the flood; *
the Lord sits as king for ever.
The Lord will give strength to his people, *
the Lord will bless his people with peace.
Glory to the Father, and to the Son, *
and to the Holy Spirit:
as it was in the beginning, is now, *
and will be for ever. Amen.
Psalm Prayer
You live for ever, Lord and King. All things of the earth justly sing your glory and honor. Strengthen your people against evil that we may rejoice in your peace and trust in your eternal promise.
Ant. The voice of the Lord, the God of majesty, echoes over the waters.
Ant. 2 Let all the earth adore you, Lord, and let it be joyful; for a new light has dawned upon the ages.
Psalm 66
Eucharistic hymn
The Lord is risen and all people have been brought by him to the Father (Hesychius).
I
Cry out with joy to God, all the earth, *
O sing to the glory of his name.
O render him glorious praise. *
Say to God: “How tremendous your deeds!
Because of the greatness of your strength *
your enemies cringe before you.
Before you all the earth shall bow; *
shall sing to you, sing to your name!”
Come and see the works of God, *
tremendous his deeds among men.
He turned the sea into dry land, *
they passed through the river dry-shod.
Let our joy then be in him; *
he rules for ever by his might.
His eyes keep watch over the nations; *
let rebels not rise against him.
O peoples, bless our God,
let the voice of his praise resound,
of the God who gave life to our souls
and kept our feet from stumbling.
For you, O God, have tested us, *
you have tried us as silver is tried:
you led us, God, into the snare; *
you laid a heavy burden on our backs.
You let men ride over our heads; †
we went through fire and through water *
but then you brought us relief.
Glory to the Father, and to the Son, *
and to the Holy Spirit:
as it was in the beginning, is now, *
and will be for ever. Amen.
Ant. Let all the earth adore you, Lord, and let it be joyful; for a new light has dawned upon the ages.
Ant. 3 Blessed be God, for he has willed that my soul should live; he has led me to a place of refuge.
II
Burnt offering I bring to your house; *
to you I will pay my vows,
the vows which my lips have uttered, *
which my mouth spoke in my distress.
I will offer burnt offerings of fatlings †
with the smoke of burning rams. *
I will offer bullocks and goats.
Come and hear, all who fear God. *
I will tell what he did for my soul:
to him I cried aloud, *
with high praise ready on my tongue.
If there had been evil in my heart, *
the Lord would not have listened.
But truly God has listened; *
he has heeded the voice of my prayer.
Blessed be God who did not reject my prayer *
nor withhold his love from me.
Glory to the Father, and to the Son, *
and to the Holy Spirit:
as it was in the beginning, is now, *
and will be for ever. Amen.
Psalm Prayer
Almighty Father, in the death and resurrection of your own Son you brought us through the waters of baptism to the shores of new life. By those waters and the fire of the Holy Spirit you have given each of us consolation. Accept our sacrifice of praise; may our lives be a total offering to you, and may we deserve to enter your house and there with Christ praise your unfailing power.
Ant. Blessed be God, for he has willed that my soul should live; he has led me to a place of refuge.
This is my beloved Son.
— Listen to him.
READINGS
FIRST READING
From the book of the prophet Isaiah
42:1-9; 49:1-9
The gentle servant of the Lord is a light to the nations
Here is my servant whom I uphold,
my chosen one with whom I am pleased,
Upon whom I have put my spirit;
he shall bring forth justice to the nations,
Not crying out, not shouting,
not making his voice heard in the street.
A bruised reed he shall not break,
and a smoldering wick he shall not quench,
Until he establishes justice on the earth;
the coastlands will wait for his teaching.
Thus says God, the Lord,
who created the heavens and stretched them out,
who spreads out the earth with its crops,
Who gives breath to its people
and spirit to those who walk on it:
I, the Lord, have called you for the victory of justice,
I have grasped you by the hand;
I formed you, and set you
as a covenant of the people,
a light for the nations,
To open the eyes of the blind,
to bring out prisoners from confinement,
and from the dungeon, those who live in darkness.
I am the Lord, this is my name;
my glory I give to no other,
nor my praise to idols.
See, the earlier things have come to pass,
new ones I now foretell;
Before they spring into being,
I announce them to you.
Hear me, O coastlands,
listen, O distant peoples.
The Lord called me from birth,
from my mother’s womb he gave me my name.
He made of me a sharp-edged sword
and concealed me in the shadow of his arm.
He made me a polished arrow,
in his quiver he hid me.
You are my servant, he said to me,
Israel, through whom I show my glory.
Though I thought I had toiled in vain,
and for nothing, uselessly, spent my strength,
Yet my reward is with the Lord,
my recompense is with my God.
For now the Lord has spoken
who formed me as his servant from the womb,
That Jacob may be brought back to him
and Israel gathered to him
And I am made glorious in the sight of the Lord,
and my God is now my strength!
It is too little, he says, for you to be my servant,
to raise up the tribes of Jacob,
and restore the survivors of Israel;
I will make you a light to the nations,
that my salvation may reach to the ends of the earth.
Thus says the Lord,
the redeemer and the Holy One of Israel,
To the one despised, whom the nations abhor,
the slave of rulers;
When kings see you, they shall stand up,
and princes shall prostrate themselves
Because of the Lord who is faithful,
the Holy One of Israel who has chosen you.
Thus says the Lord:
In a time of favor I answer you,
on the day of salvation I help you,
To restore the land
and allot the desolate heritages,
Saying to the prisoners: Come out!
To those in darkness: Show yourselves!
Along the ways they shall find pasture,
on every bare height shall their pastures be.
RESPONSORY
Matthew 3:16, 17; Luke 3:22
Today in the Jordan as the Lord was baptized,
the heavens opened and the Spirit in the form of a dove rested upon him;
the voice of the Father was heard:
— This is my beloved Son in whom I am well pleased.
The Spirit descended in visible form as a dove,
and a voice from heaven was heard:
— This is my beloved Son in whom I am well pleased.
SECOND READING
From a Sermon by Saint Gregory of Nazianzus, bishop
(Oratio 39 in Sancta Lumina, 14-16, 20: PG 36, 350-351, 354, 358-359)
The baptism of Christ
Christ is bathed in light; let us also be bathed in light. Christ is baptized; let us also go down with him, and rise with him.
John is baptizing when Jesus draws near. Perhaps he comes to sanctify his baptizer; certainly he comes to bury sinful humanity in the waters. He comes to sanctify the Jordan for our sake and in readiness for us; he who is spirit and flesh comes to begin a new creation through the Spirit and water.
The Baptist protests; Jesus insists. Then John says: I ought to be baptized by you. He is the lamp in the presence of the sun, the voice in the presence of the Word, the friend in the presence of the Bridegroom, the greatest of all born of woman in the presence of the firstborn of all creation, the one who leapt in his mother’s womb in the presence of him who was adored in the womb, the forerunner and future forerunner in the presence of him who has already come and is to come again. I ought to be baptized by you: we should also add, “and for you,” for John is to be baptized in blood, washed clean like Peter, not only by the washing of his feet.
Jesus rises from the waters; the world rises with him. The heavens like Paradise with its flaming sword, closed by Adam for himself and his descendants, are rent open. The Spirit comes to him as to an equal, bearing witness to his Godhead. A voice bears witness to him from heaven, his place of origin. The Spirit descends in bodily form like the dove that so long ago announced the ending of the flood and so gives honor to the body that is one with God.
Today let us do honor to Christ’s baptism and celebrate this feast in holiness. Be cleansed entirely and continue to be cleansed. Nothing gives such pleasure to God as the conversion and salvation of men, for whom his every word and every revelation exist. He wants you to become a living force for all mankind, lights shining in the world. You are to be radiant lights as you stand beside Christ, the great light, bathed in the glory of him who is the light of heaven. You are to enjoy more and more the pure and dazzling light of the Trinity, as now you have received—though not in its fullness—a ray of its splendor, proceeding from the one God, in Christ Jesus our Lord, to whom be glory and power for ever and ever. Amen.
RESPONSORY
Psalm 114:5
Today the heavens opened and the waters of the sea became sweet and fragrant;
the earth rejoiced, the mountains and hills exulted,
— because Christ was baptized by John in the Jordan.
What has happened that the sea has been put to flight,
and the Jordan has turned back upon itself?
— Because Christ was baptized by John in the Jordan.
Those who wish to extend the celebration of the vigil of today’s feast, according to tradition, first celebrate the Office of Readings. After both readings and before the Te Deum, they may add canticles and a gospel reading. Afterward the Te Deum is sung, the prayer is said, and the hour is concluded as in the Ordinary.
TE DEUM
You are God: we praise you;
You are the Lord: we acclaim you;
You are the eternal Father:
All creation worships you.
To you all angels, all the powers of heaven,
Cherubim and Seraphim, sing in endless praise:
Holy, holy, holy Lord, God of power and might,
heaven and earth are full of your glory.
The glorious company of apostles praise you.
The noble fellowship of prophets praise you.
The white-robed army of martyrs praise you.
Throughout the world the holy Church acclaims you:
Father, of majesty unbounded,
your true and only Son, worthy of all worship,
and the Holy Spirit, advocate and guide.
You, Christ, are the king of glory,
the eternal Son of the Father.
When you became man to set us free
you did not spurn the Virgin’s womb.
You overcame the sting of death,
and opened the kingdom of heaven to all believers.
You are seated at God’s right hand in glory.
We believe that you will come, and be our judge.
Come then, Lord, and help your people,
bought with the price of your own blood,
and bring us with your saints
to glory everlasting.
℣. Save your people, Lord, and bless your inheritance.
℟. Govern and uphold them now and always.
℣. Day by day we bless you.
℟. We praise your name for ever.
℣. Keep us today, Lord, from all sin.
℟. Have mercy on us, Lord, have mercy.
℣. Lord, show us your love and mercy;
℟. for we put our trust in you.
℣. In you, Lord, is our hope:
℟. and we shall never hope in vain.
The concluding part of the hymn may be omitted.
CONCLUDING PRAYER
Let us pray.
Almighty, eternal God,
when tSpirit descended upon Jesus
at his baptism in the Jordan,
you revealed him as your own beloved Son.
Keep us, your children born of water and the Spirit,
faithful to our calling.
We ask this through our Lord Jesus Christ, your Son,
who lives and reigns with you and the Holy Spirit,
God, for ever and ever.
— Amen.
Or:
Almighty ever-living God,
who, when Christ had been baptized in the River Jordan
and as the Holy Spirit descended upon him,
solemnly declared him your beloved Son,
grant that your children by adoption,
reborn of water and the Holy Spirit,
may always be well pleasing to you.
Through our Lord Jesus Christ, your Son,
who lives and reigns with you in the unity of the Holy Spirit,
God, for ever and ever.
— Amen.
ACCLAMATION
Let us praise the Lord.
— And give him thanks.
******
Psalm 24
The Lord’s entry into his temple
Christ opened heaven for us in the manhood he assumed (Saint Irenaeus).
The Lord’s is the earth and its fullness, *
the world and all its peoples.
It is he who set it on the seas; *
on the waters he made it firm.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Who shall climb the mountain of the Lord? *
Who shall stand in his holy place?
The man with clean hands and pure heart, †
who desires not worthless things, *
who has not sworn so as to deceive his neighbor.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
He shall receive blessings from the Lord *
and reward from the God who saves him.
Such are the men who seek him, *
seek the face of the God of Jacob.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
O gates, lift high your heads; †
grow higher, ancient doors. *
Let him enter, the king of glory!
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Who is the king of glory? †
The Lord, the mighty, the valiant, *
the Lord, the valiant in war.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
O gates, lift high your heads; †
grow higher, ancient doors. *
Let him enter, the king of glory!
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Who is he, the king of glory? †
He, the Lord of armies, *
he is the king of glory.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Glory to the Father, and to the Son, *
and to the Holy Spirit:
as it was in the beginning, is now, *
and will be for ever. Amen.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Psalm 67
People of all nations will worship the Lord
You must know that God is offering his salvation to all the world (Acts 28:28).
O God, be gracious and bless us *
and let your face shed its light upon us.
So will your ways be known upon earth *
and all nations learn your saving help.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Let the peoples praise you, O God; *
let all the peoples praise you.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Let the nations be glad and exult *
for you rule the world with justice.
With fairness you rule the peoples, *
you guide the nations on earth.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Let the peoples praise you, O God; *
let all the peoples praise you.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
The earth has yielded its fruit *
for God, our God, has blessed us.
May God still give us his blessing *
till the ends of the earth revere him.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Glory to the Father, and to the Son, *
and to the Holy Spirit:
as it was in the beginning, is now, *
and will be for ever. Amen.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Psalm 100
The joyful song of those entering God’s temple
The Lord calls his ransomed people to sing songs of victory (Saint Athanasius).
Cry out with joy to the Lord, all the earth. †
Serve the Lord with gladness. *
Come before him, singing for joy.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Know that he, the Lord, is God. †
He made us, we belong to him, *
we are his people, the sheep of his flock.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Go within his gates, giving thanks. †
Enter his courts with songs of praise. *
Give thanks to him and bless his name.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Indeed, how good is the Lord, †
eternal his merciful love. *
He is faithful from age to age.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
Glory to the Father, and to the Son, *
and to the Holy Spirit:
as it was in the beginning, is now, *
and will be for ever. Amen.
Ant. Come, let us worship Christ, the beloved Son in whom the Father was well pleased.
OPTIONAL VIGIL
CANTICLES
Ant. The Jordan River trembled as the Lord Jesus entered; from the water rose a new creation to bring light to all the world.
Canticle I: Isaiah 26:1b-4, 7-9, 12
Hymn after the defeat of the enemy
Jerusalem the Holy City has a great, high wall and twelve gates (see Revelation 21:12).
A strong city have we;
he sets up walls and ramparts to protect us.*
Open up the gates †
to let in a nation that is just, *
one that keeps faith.
A nation of firm purpose you keep in peace; *
in peace, for its trust in you.
Trust in the Lord forever! *
For the Lord is an eternal Rock.
The way of the just is smooth; *
the path of the just you make level.
Yes, for your way and your judgments, O Lord, *
we look to you;
your name and your title *
are the desire of our souls.
My soul yearns for you in the night, *
yes, my spirit within me keeps vigil for you;
When your judgment dawns upon the earth, *
the world's inhabitants learn justice.
O Lord, you mete out peace to us, *
for it is you who have accomplished all we have done.
Glory to the Father, and to the Son, *
and to the Holy Spirit:
as it was in the beginning, is now, *
and will be for ever. Amen.
Canticle II: Isaiah 40:1-8
The coming of the Lord.
The word of the Lord endures forever. This word has indeed been proclaimed to you. (1 Peter 1:25).
Comfort, give comfort to my people, *
says your God.
Speak tenderly to Jerusalem, *
and proclaim to her that her service is at an end,
her guilt is expiated; †
indeed, she has received from the hand of the Lord *
double for all her sins.
A voice cries out: *
In the desert prepare the way of the Lord!
Make straight in the wasteland a highway for our God! *
Every valley shall be filled in,
every mountain and hill shall be made low; *
the rugged land shall be made a plain,
the rough country, a broad valley. *
Then the glory of the Lord shall be revealed,
and all mankind shall see it together; *
for the mouth of the Lord has spoken.
A voice says, “Cry out!” *
I answer, “What shall I cry out?”
“All mankind is grass, *
and all their glory like the flower of the field.
The grass withers, the flower wilts, †
when the breath of the Lord blows upon it. *
(So then, the people is the grass.)
Though the grass withers and the flower wilts, *
the word of our God stands forever.”
Glory to the Father, and to the Son, *
and to the Holy Spirit:
as it was in the beginning, is now, *
and will be for ever. Amen.
Canticle III: Isaiah 66:10-14a
Joys of heaven
The heavenly Jerusalem is a free woman and our mother (Galatians 4:26).
Rejoice with Jerusalem and be glad because of her, *
all you who love her;
Exult, exult with her, *
all you who were mourning over her!
Oh, that you may suck fully *
of the milk of her comfort,
That you may nurse with delight *
at her abundant breasts!
For thus says the Lord: †
Lo, I will spread prosperity over her like a river, *
and the wealth of the nations like an overflowing torrent.
As nurslings, you shall be carried in her arms, *
and fondled in her lap;
As a mother comforts her son, †
so will I comfort you; *
in Jerusalem you shall find your comfort.
When you see this, your heart shall rejoice, *
and your bodies flourish like the grass.
Glory to the Father, and to the Son, *
and to the Holy Spirit:
as it was in the beginning, is now, *
and will be for ever. Amen.
Ant. The Jordan River trembled as the Lord Jesus entered; from the water rose a new creation to bring light to all the world.
THE HOLY GOSPEL
+ A reading from the holy Gospel according to Matthew
28:1-10, 16-20
He has risen from the dead and is going before you to Galilee
After the sabbath, as the first day of the week was dawning, Mary Magdalene and the other Mary came to see the tomb. And behold, there was a great earthquake; for an angel of the Lord descended from heaven, approached, rolled back the stone, and sat upon it. His appearance was like lightning and his clothing was white as snow. The guards were shaken with fear of him and became like dead men.
Then the angel said to the women in reply, “Do not be afraid! I know that you are seeking Jesus the crucified. He is not here, for he has been raised just as he said. Come and see the place where he lay. Then go quickly and tell his disciples, ‘He has been raised from the dead, and he is going before you to Galilee; there you will see him.’ Behold, I have told you.”
Then they went away quickly from the tomb, fearful yet overjoyed, and ran to announce this to his disciples. And behold, Jesus met them on their way and greeted them. They approached, embraced his feet, and did him homage. Then Jesus said to them, “Do not be afraid. Go tell my brothers to go to Galilee, and there they will see me.”
The eleven disciples went to Galilee, to the mountain to which Jesus had ordered them.
When they saw him, they worshiped, but they doubted.
Then Jesus approached and said to them,
“All power in heaven and on earth has been given to me.
Go, therefore, and make disciples of all nations,
baptizing them in the name of the Father,
and of the Son,
and of the Holy Spirit,
teaching them to observe all that I have commanded you.
And behold, I am with you always, until the end of the age.”
Or:
+ A reading from the holy Gospel according to Matthew
3:13-17
After Jesus was baptized, he saw the Spirit of God coming upon him
Jesus came from Galilee to John at the Jordan
to be baptized by him.
John tried to prevent him, saying,
“I need to be baptized by you,
and yet you are coming to me?”
Jesus said to him in reply,
“Allow it now, for thus it is fitting for us
to fulfill all righteousness.”
Then he allowed him.
After Jesus was baptized,
he came up from the water and behold,
the heavens were opened for him,
and he saw the Spirit of God descending like a dove
and coming upon him.
And a voice came from the heavens, saying,
“This is my beloved Son, with whom I am well pleased.”
Or:
+ A reading from the holy Gospel according to Mark
3:15-16, 21-22
You are my beloved Son, with you I am well pleased
This is what he proclaimed:
“One mightier than I is coming after me.
I am not worthy to stoop and loosen the thongs of his sandals.
I have baptized you with water;
he will baptize you with the holy Spirit.”
It happened in those days that Jesus came from Nazareth of Galilee
and was baptized in the Jordan by John.
On coming up out of the water he saw the heavens being torn open
and the Spirit, like a dove, descending upon him.
And a voice came from the heavens,
“You are my beloved Son; with you I am well pleased.”
A homily on the Gospel may be given.
Te Deum