Reasons For Killing

Tunc Herodes videns quomodo illusus esset a magis, iratus est valde, et mittens occidit omnes pueros, qui erant in Bethlehem et in omnibus finibus ejus, a bimatu et infra. Verisimile est ergo, quod postquam Herodi magi nihil renuntiaverunt, eum credere potuisse illos fallacis stellae visione deceptos, posteaquam non invenerunt quem natum putaverant, erubuisse ad se redire, atque ita eum, timore depulso, ab inquirendo ac persequendo puero quievisse. Cum ergo post purgationem matris ejus, in Jerusalem cum illo venissent, et ea gesta essent in templo, quae a Luca narrantur, quia verba Simeonis et Annae de illo prophetantium, cum coepissent ab eis qui audierant praedicari, ad pristinam intentionem revocatura erant animum regis, admonitus per somnum Joseph cum infante et matre ejus fugit in Aegyptum. Deinde vulgatis rebus, quae in templo dictae factaeque fuerant, Herodes a magis se sensit illusum, ac deinde ad Christi mortem cupiens pervenire multos infantes, sicut Matthaeus narrat, occidit in Bethlehem, et in omnibus finibus ejus, et hoc a bimatu et infra. Quia crudelitas animi per invidiam et furorem exardescens, modum in nullo tenuit, sed malitia omnes superare contendit. Nam non contenta est sola vastatione Bethlehem, sed et omnes simul ejus fines devastavit, nec etiam parvulae aetatis ullam misericordiam habuit, quin omnes a filio unius noctis usque ad filium duorum annorum pariter occidit. Rabanus Maurus, Commentariorum In Matthaeum, Liber I Source: Migne PL 107.762b-d

Then Herod, seeing how he was deceived by the Magi, was greatly angered, and he ordered all the young boys who were in Bethlehem to be killed, and in all the surrounding region, from two years and under. 1 It is therefore likely to be true that after the Magi had not reported back to Herod, that he thought that they had been deceived by their seeing of a misleading star, and after they had not found the boy whom they thought they would, they were too embarrassed to return to him, and thus he who was struck by fear because of the questions about the boy and the seeking of him, was placated. But after the purification of His mother, when they came with Him to Jerusalem, and those things happened in the temple about which Luke tells us, the words of Simeon and Anna making prophecy about Him, when these things began to be told by those who had heard them, the soul of the king was recalled to its former intention, and therefore Joseph was warned in a dream to flee with the child and his mother into Egypt. Then with the things that were said and done in the temple spreading abroad, Herod felt he had been made sport of by the Magi, and desiring the death of Christ, he decided to kill the many infants in Bethlehem of two years and under, and in all the surrounding region, as Matthew says. 2 Because the cruelty of a soul blazes up through envy and anger, he held to no moderation, but strove to overcome all things with evil. For he was not content with the devastation of Bethlehem alone, but at the same time even all the surrounding region, having no pity at all on the little ones, since he slew every one of them, from the son of one night, even to the son of two years. Rabanus Maurus, Commentary On The Gospel of Saint Matthew, Book 1 1 Mt 2.16 2 cf Augustine De Consensu Evang 2.11