Almighty God commands all men to worship him.  He does this not in order to gain something for himself from the worship, but because his worshipers will.  Through the worship of God the mortal mind becomes detached from the distractions and temptations of this world and grows in the grace and freedom of God to love and for his capacity to experience love to grow.  Hildebert (d. 1133), archbishop of Tours, in France was among many medieval writers to produce works on the Holy Mass.  In the following extract, he gives reasons for why the Mass is offered, and then gives the reasons why it is offered every day.

"The Mass is celebrated for many reasons.  First, that we may pray to God.  Second, that God may receive our prays and oblations.  Third, to set before God the offerings made for the dead.  Fourth, for the kiss of peace.  Fifth, that the offerings may be sanctified.  Sixth, that the offering of the Body and Blood of Christ may be confirmed by the Holy Spirit.  Seventh, that the Our Father may be sung.  Now, the Our Father contains seven petitions: three spiritual and four temporal.  The Lord first taught this prayer to his disciples and Apostles.  Joel 2, 32, says of this prayer: 'Whoever shall call upon the Name of The Lord, shall be saved.'  The petitions are seven in number according to the number of the gifts of the Holy Spirit, or according to the levels in the hierarchy of the Church.  Why should this offering of the Mass be made again every day, since Christ saved the world through his Passion, and he is no longer subject to death?  For many reasons.  First, because we sin every day.  Second, because it is ordered that the Body of Christ be offered for sinners after their sins, that they might find salvation through the Body of Christ, and that they might go forth after their repentance.  Third, that the great benefit of the Passion of Christ not be forgotten.  Fourth, that it might foreshadow the Day of Judgment, on which the just will be separated from the unjust."