Are there any angels sent by God to protect men?
Yes, there are certain angels sent by God to protect men, for it is a part of the ruling of Divine Providence that man, whose thoughts and wishes are so changeable andsoinconstant, should be assisted in his journey towards heaven by one of the blessed spirits whose wills are for ever rooted in good (CXIII. 1).
Has God deputed one and the same angel to be the guardian of several men, or has he deputed a guardian angel for each separate man?
God has deputed a guardian angel to assist each separate man; for every single human soul is more dear to God than the divers species of material creatures over which, however, presides an angel who is mindful of them, and promotes their welfare (CXIII. 3).
To what order belong the angels which are thus deputed by God, separately, to be the guardian angels to men?
The angels which are thus deputed by God, separately, to be the guardian angels to men belong all to the last of the nine choirs of angels (CXIII. 3).
Are all men without exception thus committed by God to the care of one of His angels?
Yes, all men without exception are thus committed by God to the care of one of His angels, as long as they live on this earth, and the reason is because of the perilous way through which all must pass before they come to the end of their lives (CXIII. 4).
Did Christ our Lord, as man, also have a guardian angel?
No, it was not fitting that Christ our Lord should have a guardian angel, seeing that in person He was God; but certain angels were appointed to the great honour of ministering to Him (CXIII. 4, Obj. 1).
When is an angel personally appointed by God to be the guardian of some man?
It is at the instant of man's coming into the world that God deputes an angel to be his guardian (CXIII. 5).
Does it happen that sometimes an angel quits a man to whose guardianship he has been appointed?
No, a guardian angel never leaves a man over whom he has charge, and he continues to watch over him~, without ceasing, until the last moment of his life on earth (CXIII. 6).
Do the angels ever sorrow because of the sins of those over whom they have charge?
No, for after doing what lies in their power to prevent sin, should sin nevertheless prevail, they adore, in this as in all things else, the inscrutability of the divine plan (CXIII. 7).
Is it a commendable thing to counsel the practice committing oneself often and in all things to the protection of one's guardian angel?
Yes, to counsel the practice of commending oneself often and in all things to the protection of one's guardian angel is an excellent thing, and should be recommend in every way.
May one be infallibly certain of this protection, should one invoke it?
Yes, provided that our demand is consistent with the eternal counsels of God, and according as our concerns are ordained to the glory of God (CXIII. 8).
Next - The Catechism of the Summa - XXV. OF THE ACTION OF THE BAD ANGELS OR OF THE DEMONS
(This is no longer being shared from the Kindle edition. I'm now sharing from the Jacques Maritain Center, at the University of Notre Dame.)