Prayer before Mass - Aquinas

One of my favorites.

Almighty and everlasting God, behold I come to the Sacrament of Thine only-begotten Son, our Lord Jesus Christ: I come as one infirm to the physician of life, as one unclean to the fountain of mercy, as one blind to the light of everlasting brightness, as one poor and needy to the Lord of heaven and earth. Therefore I implore the abundance of Thy measureless bounty that Thou wouldst vouchsafe to heal my infirmity, wash my uncleanness, enlighten my blindness, enrich my poverty and clothe my nakedness, that I may receive the Bread of Angels, the King of kings, the Lord of lords, with such reverence and humility, with such sorrow and devotion, with such purity and faith, with such purpose and intention as may be profitable to my soul’s salvation. Grant unto me, I pray, the grace of receiving not only the Sacrament of our Lord’s Body and Blood, but also the grace and power of the Sacrament. O most gracious God, grant me so to receive the Body of Thine only-begotten Son, our Lord Jesus Christ, which He took from the Virgin Mary, as to merit to be incorporated into His mystical Body, and to be numbered amongst His members. O most loving Father, give me grace to behold forever Thy beloved Son with His face at last unveiled, whom I now purpose to receive under the sacramental veil here below.
Amen.