Festum Sanctissimi Corporis Christi

The immeasurable benefits, which the goodness of God hath bestowed on Christian people, have conferred on them also a dignity beyond all price. "For what nation is there so great, who hath gods so nigh unto them, as the Lord, our God, is unto us?" Deut. iv. 7. The Only-begotten Son of God, being pleased to make us "partakers of the Divine nature," 2 Pet. i. 4, took our nature upon Him, being Himself made Man that He might make men gods. And all, as much of ours as He took, He applied to our salvation. On the Altar of the Cross He offered up His Body to God the Father as a sacrifice for our reconciliation He shed His Blood as the price whereby He redeemeth us from wretchedness and bondage, and the washing whereby He cleanseth us from all sin. And for a noble and abiding memorial of that so great work of His goodness, He hath left unto His faithful ones the Same His very Body for Meat, and the Same His very Blood for Drink, to be fed upon under the appearance of bread and wine.

How precious a thing then, how marvelous, how health-giving, how furnished with all dainties, is the Supper [of the Lord!] Than His Supper can anything be more precious? Therein there is put before us for meat, not, as of old time, the flesh of bulls and of goats, but Christ Himself, our very God. Than this Sacrament can anything be more marvelous? Therein it cometh to pass that bread and wine are bread and wine no more, but in the stead thereof there is the Body and there is the Blood of Christ; that is to say, Christ Himself, Perfect God and Perfect Man, Christ Himself is there, under the appearance of a little bread and wine. His faithful ones eat Him, but He is not mangled; nay, when [the veil which shroudeth Him in] this Sacrament is broken, in each broken piece thereof remaineth whole Christ Himself, Perfect God and Perfect Man. All that the senses can reach in this Sacrament, [look, taste, feel, smell, and the like, all these] abide of bread and wine, but the Thing is not bread and wine. And thus room is left for faith; Christ Who hath a Form That can be seen, is here taken and received not only unseen, but seeming to be bread and wine, and the senses, which judge by the wonted look, are warranted against error.

Than this Sacrament can anything be more health-giving? Thereby are sins purged away, strength renewed, and the soul fed upon the fatness of spiritual gifts. This Supper is offered up in the Church both for the quick and dead it was ordained to the health of all, all get the good of it. Than this Sacrament can anything be more furnished with dainties The glorious sweetness thereof is of a truth such that no man can fully tell it. Therein ghostly comfort is sucked from its very well-head. Therein a memorial is made of that exceeding great love which Christ showed in time of His sufferings. It was in order that the boundless goodness of that His great love might be driven home into the hearts of His faithful ones, that when He had celebrated the Passover with His disciples, and the last Supper was ended, "the Lord Jesus, knowing that His hour was come that He should depart out of this world unto the Father, having loved His own which were in the world, He loved them unto the end," John xiii. 1, and instituted this Sacrament, this Sacrament, the everlasting "forth-showing of His death until He come again," 1 Cor. xi. 26, this Sacrament, the embodied fulfilment of all the ancient types and figures, this Sacrament, the greatest miracle which He ever wrought, and the one mighty joy of them that now have sorrow, till He shall come again, and their heart shall rejoice, and their joy no man take from them. John xvi. 22.

- From the Sermons of St. Thomas Aquinas 

Saint Margaret of Scotland

Margaret, of the royal house of England, was born in Hungary and 
 spent her childhood there as an unusually devout and pious girl. When her father was called to high office in his own country by his uncle, St. Edward, King of England, she went to England and then to Scotland. There, upon instructions from her mother, she married King Malcolm III. The country was blessed by her holy life and by her deeds of charity for the next thirty years. The austerity of her life was exceedingly great, and her charity towards her neighbour most ardent and zealous, especially for those in need, for whom she not infrequently exhausted the treasury. At length, having most patiently endured bitter sorrows and long illness, she rendered her soul to God on the 16th day of November. At the moment of her death her features, emaciated and pale, bloomed again with unusual beauty. On the authority of Clement X she was chosen Patroness of Scotland, and is honoured with great devotion throughout the world. 

- Roman Martyrology 

Let us pray.
O God, Who didst make Margaret, that blessed Queen, wonderful for tender love toward the poor, grant that her intercession and example may be effectual to gain for our hearts a thorough love toward thee.
Through Jesus Christ, thy Son our Lord, Who liveth and reigneth with thee, in the unity of the Holy Ghost, ever one God, world without end.
R. Amen.

For the feast of the Most Blessed Trinity recite the Athanasian Creed

Canticum Quicumque [4]
(Canticum Quicumque * Symbolum Athanasium) 
Whosoever willeth to be saved, * before all things it is necessary that he hold the Catholic faith.
Which faith except every one do keep whole and undefiled, * without doubt he shall perish eternally.
Now the Catholic faith is this, * that we worship one God in Trinity, and Trinity in Unity.
Neither confounding the Persons, * nor dividing the substance.
For there is one Person of the Father, another of the Son, * and another of the Holy Ghost.
But the Godhead of the Father, of the Son, and of the Holy Ghost is one, * the Glory Equal, the Majesty Co-Eternal.
Such as the Father is, such is the Son, * and such is the Holy Ghost.
The Father Uncreated, the Son Uncreated, * and the Holy Ghost Uncreated.
The Father Infinite, the Son Infinite, * and the Holy Ghost Infinite. * The Father Eternal, the Son Eternal, * and the Holy Ghost Eternal.
And yet they are not three Eternals, * but one Eternal.
As also they are not three Uncreated, nor three Infinites, * but One Uncreated, and One Infinite.
So likewise the Father is Almighty, the Son Almighty, * and the Holy Ghost Almighty.
And yet they are not three Almighties, * but One Almighty.
So the Father is God, the Son God, * and the Holy Ghost God.
And yet they are not three Gods, * but One God.
So the Father is Lord, the Son Lord, * and the Holy Ghost Lord.
And yet they are not three Lords, * but One Lord.
For, like as we are compelled by Christian truth to acknowledge every Person by Himself to be God and Lord, * so are we forbidden by the Catholic Religion to say, there be three Gods or three Lords.
The Father is made of none, * neither created, nor begotten.
The Son is of the Father alone: * not made, nor created, but begotten.
The Holy Ghost is of the Father, and the Son: * not made, nor created, nor begotten, but proceeding.
So there is One Father, not three Fathers; one Son, not three Sons; * one Holy Ghost, not three Holy Ghosts.
And in this Trinity is nothing afore or after, nothing is greater or less; * but the whole three Persons are Co-Eternal together, and Co-Equal.
So that in all things, as is aforesaid, * the Unity in Trinity, and the Trinity in Unity is to be worshipped.
He therefore that willeth to be safe, * let him thus think of the Trinity.
But it is necessary to eternal salvation, * that he also believe faithfully the Incarnation of our Lord Jesus Christ.
The right Faith therefore is, that we believe and confess, * that our Lord Jesus Christ, the Son of God, is God and man.
God, of the Substance of the Father, Begotten before the worlds: * and Man, of the substance of His mother, born in the world.
Perfect God, Perfect Man, * of a reasoning soul and human flesh subsisting.
Equal to the Father as touching His Godhead, * inferior to the Father as touching His Manhood.
Who, although He be God and Man, * yet He is not two, but One Christ.
One, however, not by conversion of the Godhead into Flesh, * but by taking of the Manhood into God.
One altogether, not by confusion of Substance, * but by Unity of Person.
For as the reasoning soul and flesh is one man, * so God and man is One Christ.
Who suffered for our salvation, descended into hell, * rose again the third day from the dead.
He ascended into heaven, He sitteth on the right hand of the Father, God Almighty, * from whence He shall come to judge the quick and the dead.
At whose coming all men shall rise again with their bodies, * and shall give account for their own works.
And they that have done good shall go into life eternal, * but they that have done evil into eternal fire.
This is the Catholic Faith, * which except a man believe faithfully and firmly, he cannot be saved.

The Most Blessed Trinity

 Glory be to the Father, and to the Son, and to the Holy Ghost, now and forever. Amen.

Saint Fulgentius, Bishop [of Ruspa]

Found in the Works of Augustine, tom. 3

“The Faith which the holy Patriarchs and Prophets received from God before His Son was made Flesh, the Faith which the holy Apostles heard from the Lord Himself when Present in the Flesh, the Faith which the same Apostles learnt by the teaching of the Holy Ghost not only to preach by word of mouth, but also to leave behind them in their writings for the healthful instruction of all that should come after, that Faith teacheth that the Trinity, that is to say, the Father, the Son, and the Holy Ghost, is but One God. But we could not truly call the Father, the Son, and the Holy Ghost a Trinity, if One and the Selfsame Person were named Father, Son, and Holy Ghost.

“Nor if as the Being of the Father, the Son, and the Holy Ghost is One Being, so were there but One Person, then were it untrue to say that God is a Trinity. On the other hand, if, as the Persons of the Father, the Son, and the Holy Ghost are distinguished One from Another by that which is proper to Each, so were They diverse by difference of nature, then were it untrue to say that God is One. But since concerning the nature of the One True God, Who is a Trinity, it is the Truth to say that God is One, and the Truth to say that God is a Trinity, therefore the True God is a Trinity in Persons, and an Unity in nature.

“Through this Oneness of nature All That the Father is is in the Son and the Holy Ghost, All That the Son is is in the Father and the Holy Ghost, and All That the Holy Ghost is is in the Father and the Son. Of the Father, the Son, and the Holy Ghost, None is without Other, None is before Other, None is Greater than Other, None is Mightier than Other. The Father, as touching the One Divine Nature, is neither before nor greater than the Son and the Holy Ghost neither is it possible that the Eternity and Infinity of the Son, whether as before or greater, should be before or greater than the Eternity and Infinity of the Spirit.“