Caption: butchers slaughter babies.
The Church mourns and has kept the feast of the Holy Innocents since about the fifth century.
From the Roman Missal:
"Out of the mouths of infants and of sucklings, O God, Thou hast perfected praise, because of Thy enemies. Ps. O Lord our God, how admirable is Thy name in the whole earth!"
Image panel from the choir of the Milan Duomo.