Today the Church commemorates the Holy Guardian Angels. "And so the angels are here; they are at your side, they are with you, present on your behalf. They are here to protect you and to serve you. ... So let us be devoted and grateful to such great protectors; let us return their love and honor them as much as we can and should." (Saint Bernard of Clairvaux, Sermon 12).
This observance is a relative latecomer to the calendar. It
apparently appeared first in Spain in the 16th century from where it spread to
the wider Church until finally in 1670 it
was inscribed in the universal calendar for this date.
The Church's belief in the assistance of our Guardian Angels is, of course, considerably older. In the Gospel, Jesus famously instructs his disciples not to despise these little ones, whose angels in heaven always look upon the face of my heavenly Father (Matthew 18:10), and in his Commentary on Matthew, Saint Jerome suggested that each soul has such an angel to guard it, a view reaffirmed by Saint Thomas Aquinas.
In popular piety, there may be an unfortunate tendency to treat this as a topic for children - a tendency exacerbated, perhaps, by the popular children's prayer, Angel of God, my Guardian dear. But, as is often the case, the liturgy provides a better guide to understanding this observance. It honors the Guardian Angels in the context of God's unfathomable providence. Fittingly, the proper 1st reading for today's Mass (Exodus 23:20-23) takes us back to the Israelites in the desert: I am going to send an angel in front of you, to guard you on the way and to bring you to the place that I have prepared.
Coincidentally, tonight, our Jewish brothers and sisters begin the week-long festival of Sukkot, (what the New Testament typically calls the "Feast of Tabernacles" or "Feast of Booths"). Originally a fall harvest thanksgiving festival, it became a commemoration of the 40 years the people lived of Israel in tents in the desert. (One of three Old Testament "pilgrimage feasts," this was the festival Jesus for which went to Jerusalem in John 7. also coincidentally, it was earlier in also in Exodus 23 that God for the first time commanded his people to observe Sukkot: You shall observe the festival of ingathering at the end of the year, when you gather in from the field the fruit of your labor.)
These references remind us that, like the Jewish festival of Sukkot, the Church's faith in the Holy Guardian Angels is about something very fundamental, God's providential protection and care for his people in all places and at all times, in both the great and the small matters of life. Obviously, a renewed confidence in God's providential protection and care for each one of us is increasingly important in this dangerous and challenging time in which we currently find ourselves.