Angels are servants and messengers from God. "Angel" in Greek means messenger. In unseen ways the angels help us on our earthly pilgrimage by assisting us in work and study, helping us in temptation and protecting us from physical danger.
The idea that each soul has assigned to it a personal guardian angel has been long accepted by the Church and is a truth of our faith. From the Gospel of today's liturgy we read: "See that you never despise any of these little ones, for I tell you that their angels in heaven are continually in the presence of my Father in heaven" (Matthew 18:10). The Catechism of the Catholic Church states that "the existence of the spiritual, non-corporeal beings that Sacred Scripture usually calls 'angels' is a truth of faith (328)." From our birth until our death, man is surrounded by the protection and intercession of angels, particularly our guardian angel: "Beside each believer stands an angel as protector and shepherd leading him to life (336)." The Church thanks God for our helpers, the angels, particularly on this feast day and September 29. Today's feast appeared in Spain during the sixteenth century. It was extended to the universal Church and made obligatory in 1670.
"Be alert in your every action as one should be who is accompanied by angels in all your ways, for that mission has been enjoined upon them. In whatever lodging, in whatever nook or corner you may find yourself, cherish a reverence for your guardian angel. In his presence do not dare to do anything you would not do in mine. Or do you doubt his presence because you do not see him? Would it really help if you did hear him, or touch him, or smell him? Remember, there are realities whose existence has not been proven by mere sight.~from Catholic Culture
"Brethren, we will love God's angels with a most affectionate love; for they will be our heavenly co-heirs some day, these spirits who now are sent by the Father to be our protectors and our guides. With such bodyguards, what are we to fear? They can neither be subdued nor deceived; nor is there any possibility at all that they should go astray who are to guard us in all our ways. They are trustworthy, they are intelligent, they are strong — why, then, do we tremble? We need only to follow them, remain close to them, and we will dwell in the protection of the Most High God. So as often as you sense the approach of any grave temptation or some crushing sorrow hangs over you, invoke your protector, your leader, your helper in every situation. Call out to him and say: Lord, save us, we are perishing." — St. Bernard