From Saint Andrew Daily Missal
The Feast of the Holy Innocents dates back to about the fifth century. The massacre of these infants manifests the royal character of Jesus. It is because Herod believed the words of the Magi and those of the High Priests whom he consulted that he sees a rival in the Infant of Bethlehem and jealously pursues Him “that is born King of the Jews.” But as the Church sings, in the Hymn for Vespers of the Epiphany, “O cruel Herod, why thus fear, Thy King and God who comes below? No earthly crown comes He to take, who heavenly kingdoms doth bestow.”
It is this God-King that the Innocents by dying confess (Collect). Their passion is the exaltation of Christ. And the praise that they render to God is a subject of confusion in the enemies of Jesus (Introit), for, far from attaining their object, they only served to fulfil the saying of the Prophet “out of Egypt have I called my son.”, and that at Bethlehem would be heard the lamentations of the mothers mourning for their children. To picture their desolation in more vivid colours, Jeremias recalls Rachel whose lamentations are heard in Rama, bewailing her children because they are not. Like a compassionate mother, the Church robes her priests today in vestments of mourning.
Let us show forth in holiness of life, the divinity of Christ, that was confessed by the death of these innocent children.
Ex ore infántium Deus, et lacténtium perfecísti laudem propter inimícos tuos. * Dómine Dóminus noster: quam admirábile est nomen tuum in univérsa terra!
Out of the mouth of infants and of sucklings, O God, Thou hast perfected praise because of Thine enemies. * O Lord our God: how admirable is Thy name in the whole earth!
(Psalm 8:3,2 from the Introit of Mass)
Deus, cujus hodiérna die præcónium Innocentes Mártyres non loquéndo, sed moriéndo conféssi sunt: ómnia in nobis vitiórum mala mortífica; ut fidem tuam, quam lingua nostra lóquitur, étiam móribus vita fateátur.
O God, Whose praise the martyred innocents did this day proclaim, not by speaking, but by dying, do to death in us all the malice of sinfulness, that our lives may also proclaim Thy faith, which our tongues profess.