An Angelic Guard

Παρεμβαλεῖ ἄγγελος Κυρίου κύκλῳ τῶν φοβουμένων αὐτὸν, καὶ ῥύσεται αὐτους.   Παντὶ πεπιστευκότι εἰς τὸν Κύριον ἄγγελος παρεδρεύει, ἐὰν μήποτε αὐτὸν ἡμεῖς ἐκ τῶν πονηρῶν ἔργων ἀποδιώξωμεν. Ὡς γὰρ τὰς μελίσσας καπνὸς φυγαδεύει, καὶ τὰς περιστερὰς δυσωδία ἐξελαύνει· οὕτω καὶ τὸν φύλακα τῆς ζωῆς ἡμῶν ἄγελλον ἡ πολύδρακυς καὶ δυσώδης ἀφιστησιν ἁμαρτία. Ἐὰν ἔχῃς ἐν τῇ ψυχῇ ἄξια φυλακῆς ἀγγελικῆς ἔργα, καὶ νοῦς πλούσιος ἐν τοῖς τῆς ἀληθείας θεωρήμασιν ἐνοικῇ σοι διὰ τὸν πλοῦτον τῶν τιμίων ἔρων τῆς ἀρετῆς, ἀναγκαίως φρουρούς σοι καὶ φύλακας παρακαθίστησιν ὁ Θεὸς, καὶ περιτειχίζει σε φυλακῇ ἀγγέλων. Σκόπει δὲ ἠλίκη ἐστὶ τῶν ἀγγέλων ἡ φύσις· ὅτι ὅλῳ σρατοπέδῳ καὶ παρεμβολῇ πολυανθρώπῳ παρεικάζεται ὁ εἰς ἄγγελος. Διὰ μὲν οὔν τὸ μέγεθος τοῦ φυλάσσοντός σε παρεμβολήν σοι χαρίζεται ὁ Κύριος· διὰ δὲ τὴν ἰσχὺν τοῦ ἀγγέλου οἰονεὶ περιτειχίζει σε πάντοθεν τῇ ἀπ' αὐτοῦ ἀσφαλείᾳ. Τοῦτο γὰρ σημαίνει τὸ Κύκλῳ. Ὥσπερ γὰρ οἱ τῶν πόλεων περίβολοι, κύκλῳ πάσαις περικείμενοι, πάντοθεν τὰς τῶν πολεμίων προσβολὰς ἀπείργουσιν· οὕτω καὶ ὁ ἄγγελος, καὶ προτειχίζει ἐκ τῶν ἔμπροσθεν, καὶ ὀπισθοφυλακεῖ, καὶ οὐδὲ τὰ ἐκατέρωθεν ἀφύλακτα καταλείπει. Διὰ τοῦτο Πεσεῖται ἐκ τοῦ κλίτους σου χιλιὰς, καὶ μυριὰς ἐκ δεξιῶν σοῦ· πρὸς σὲ δὲ οὐδὲ πληγή τινος τῶν ἐχθρῶν ἐγγιεῖ, ὅτι τοῖς ἀγγέλοις αὐτοῦ ἐντελεῖτα περὶ σου. Ἅγιος Βασίλειος ὁ Μέγας, Ὁμιλία Ἐις Τους Ψαλμούς, Εἰς Τον ΛΓ' Ψαλμον  Source: Migne PG 29.364b-c

The angel of the Lord he sets in a camp around those who fear him and he delivers them. 1 The angel assists all who believe in the Lord, if we do not expel him by depraved works. For as bees are driven off by smoke and doves by foul odors, so the guardian of our life is tearfully driven away by the foul stench of our sins. If you would have the worthy works of a guardian angel in your soul, and a mind rich in the contemplation of truth in you because of the riches of the famed works of virtue, God will certainly give watchers and guards to guard you and wall you about with a guard of angels. Consider how great is the nature of angels, that one angel is compared to a whole army and a camp set with soldiers. Thus on account of the greatness of the one who guards you, the Lord bestows a camp upon you, for the strength of the angel is a protection like a wall encircling you. This is what 'a camp around' signifies. For as the walls of cities are in a circuit surrounding all the parts of the city in order to repulse the assault of enemies from every direction, so indeed is an angel set at the front and is on guard at the back, that there be no direction unguarded. For which reason it is said, 'There fell at my left side two thousand, and ten thousand at my right.'  2 To you indeed no blow of any enemy shall come near, because he has commanded his angels concerning you. 3 Saint Basil of Caesarea, Homilies on the Psalms, from Psalm 33 1 Ps 33.8 2 Ps 90.7 3 Ps 90.10-11