From a sermon by Saint Bernard, abbot...

"He has given his angels charge over you to guard you in all your ways.  These words should fill you with respect, inspire devotion and instill confidence, respect for the presence of angels, devotion because of their loving service, and confidence because of their protection.  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.  But even if it is God who has given them this charge, we must nonetheless be grateful to them for the great love with which they obey and come to help us in our great need."

(Taken in part from today's OOR Reading in Divine Office.)