Homily by St. Hilary, Bishop of Poitiers. Comm. on Matth. xviii. (Roman Breviary: Holy Guardian Angels)

Unless thou become as little children, saith the Lord, ye shall not enter into the kingdom of heaven, that is, unless by the uprooting of bodily and mental depravity, we bring our souls to the innocency of childhood. But He giveth the name of children to all such as believe by the hearing of faith. Children follow their father, love their mother, know not how to wish evil to their neighbours, are not careful for earthly riches; they insult not, they hate not, they lie not, they believe what they are told, and take for truth what they hear. Us then it behoveth to return to the simpleness of little children, for when we are well rooted therein, we shall so far bear about in ourselves an image of the sublime simpleness of the Lord Jesus.

Woe unto the world because of offences! The lowliness of the Passion is an offence unto the world. Such is the state of stupidity to which man's ignorance hath reduced itself, that it turneth away from the Lord of Eternal Glory, because of the unsightliness of the Cross! And what is so certain to bring woe unto the world as to turn away from Christ? And therefore, He saith It must needs be that offences come, because his fulfilling the lowliness of the Passion was the predestined mean whereby He was to give us eternal life.

Take heed that ye despise not one of these little ones that believe in Me. He hath laid on us a most meet tie to constrain us to love one another, especially such as indeed believe in the Lord. For I say unto you that in heaven their Angels do always behold the face of My Father Which is in heaven. For the Son of Man is come to save that which was lost. From these words we see, first, that the Son of Man saveth; secondly, that the Angels do see God; and thirdly, that the Angels of these little ones have the wardship over the prayers of the faithful. That the Angels have this wardship is taught us absolutely. The Angels therefore do every day offer to God the prayers, which they which are saved, do make to Him in the Name of Christ. Therefore, it is dangerous for a man to despise them, seeing that these are they by whose watchful service and ministry his wishes and requests are presented before the throne of the eternal and unseen God.