Oh, how delighted are the Angels to accompany us to Holy Mass. How eagerly they do all they can to keep us from in-attention or irreverence. We know that at least there are as many Angels in the Church as there are people, since everyone has his/hers Guardian Angel at his side to aid him in his prayers and with him to adore Christ present on the Altar. So, see to it that you ask your Guardian Angel to assist at Mass with you and for you, and in your name to worship the Divine Victim, to offer Him to God, to implore His Grace. In this way, what is lacking in your devotion and attention will be made good by him and the Holy Sacrifice will by more acceptable to God Almighty.

Besides the Guardian Angels, thousands of celestial Spirits from the higher choir of Angels assist at Mass, reverently worshiping their Lord and God in this sublime Mystery. It was revealed to St. Mechtilde that three thousand Angels from the 7th Choir, the Thrones, are ever in devout attendance around every Tabernacle where the Blessed Sacrament is reserved. Doubtless a much greater number are present at Holy Mass which is not merely a Sacrament but a Sacrifice also.

St. Gregory: "The Heavens open and multitudes of Angels come to assist at the Holy Sacrifice."

St. Augustine: "The Angels surround and help the priest when he is celebrating Mass."

St. John Chrysostom: "When Mass is being celebrated, the Sanctuary is filled with countless Angels, who adore the Divine Victim immolated on the altar."

The value of the Mass is so wonderful, God's mercy and generosity are then so unlimited, that there is no moment so encouraging to ask for favors as when Jesus is sacrificed on the alter. What we ask we shall almost certainly receive, and what we do not obtain in the Mass we may scarcely hope to receive by all other prayers, penances or pilgrimages.

The Angels know this full well and come in multitudes to adore God and make their petitions at this hour of mercy.

We read in the revelations of St. Bridget: "One day when I was assisting at the Holy Sacrifice, I saw an immense number of Holy Angels descend and gather around the altar, contemplating the priest. They sang heavenly canticles that ravished my heart; Heaven itself seemed to be contemplating the great Sacrifice. And yet we poor, blind and miserable creatures assist at the Mass with so little love, relish and respect! Oh, if God would open our eyes, what wonders should we not see!"

When Blessed Henry Suso, the holy Dominican, was saying Mass, Angels in visible form gathered around the altar, and some came near to him in raptures of love. This is what takes place at every Mass, though we do not see it. Do we as Catholics ever think of this amazing truth?
At Mass we are praying in the midst of thousands of God's Angels.

Source: Mary Help Of Christians.