Preparation for Mass
St. Ambrose

Lord, Jesus Christ, I approach your banquet table in fear and trembling, for I am a sinner, and dare not rely on my own worth but only on your goodness and mercy. I am defiled by many sins in body and soul, and by my unguarded thoughts and words. Gracious God of majesty and awe, I seek your protection, I look for your healing, poor troubled sinner that I am, I appeal to you, the fountain of all mercy. I cannot bear your judgment, but I trust in your salvation. Lord, I show my wounds to you and uncover my shame before you. I know my sins are many and great, and they fill me with fear, but I hope in your mercies, for they cannot be numbered. Lord Jesus Christ, eternal King, God and man, crucified for mankind, look upon me with mercy and hear my prayer, for I trust in you. Have mercy on me, full of sorrow and sin, for the depth of your compassion never ends. Praise to you, saving sacrifice, offered on the wood of the cross for me and for all mankind. Praise to the noble and precious blood, flowing from the wounds of my crucified Lord Jesus Christ and washing away the sins of the whole world. Remember, Lord, your creature, whom you have redeemed with your blood. I repent my sins, and I long to put right what I have done. Merciful Father, take away all my offenses and sins; purify me in body and soul, and make me worthy to taste the holy of holies. May your body and blood, which I intend to receive, although I am unworthy, be for me the remission of my sins, the washing away of my guilt, the end of my evil thoughts, and the rebirth of my better instincts. May it incite me to do the works pleasing to you and profitable to my health in body and soul, and be a firm defense against the wiles of my enemies. Amen.

Thanksgiving after Mass
St. Thomas Aquinas

I thank you, holy Lord, almighty Father, eternal God, who deigned to feast me, sinful and unworthy servant, with the precious body and blood of your Son, Jesus Christ our Lord, not for any merit of mine, but only because of your merciful goodness. And I pray that this Holy Communion, far from condemning me to punishment, may bring about my pardon and salvation, encompassing me with the armor of faith and the shield of a good will. By it let my vices be done away, all lustful desires extinguished. May it advance me in charity, patience, humility, obedience, and every other virtue. Let it be strong defense against the wiles of all my enemies, visible and invisible, allaying for me every disturbance of flesh and spirit, binding me firmly to you, the one true God, and bringing my last hour to a happy close. I pray, too, that it may be your pleasure to call my sinful self one day to that banquet, wonderful past all telling, where you, with your Son and the Holy Spirit, feast your saints with the vision of yourself, who are true light, the fulfillment of all desires, the joy that knows no ending, gladness unalloyed, and perfect bliss: through the same Christ our Lord. Amen.