John Chrysostom

"Then Herod, when he had privily called the wise men, inquired of them diligently what time the star appeared:" Attempting to slay that which was born, an act of extreme folly not of madness only; since what had been said and done was enough to have withholden him from any such attempt. For those occurrences were not after the manner of man. …

Homily on the Gospel of Matthew 7 ↗

Theophylact of Ohrid

Then Herod summoned the Magi secretly. He summoned them secretly on account of the Jews, for he suspected that perhaps the Jews would highly esteem the Child and devise means to save Him as their future liberator. Therefore Herod meets with the Magi secretly. And carefully ascertained from them what time the star had appeared. That is, he learned the exact time. The star had appeared to the Magi before the Lord was born. …

Commentary on Matthew ↗

Gregory the Dialogist

But when the birth of our King became known, Herod turned to cunning schemes, lest he be deprived of his earthly kingdom.

Forty Gospel Homilies, Homily 10 ↗

Thomas Aquinas

Then inquiry is made about the person of the newly-born (v. 7). First, the inquiry is presented; secondly, the discovery (v. 11); thirdly, the veneration of the child (v. 11b). They were moved to search for the person for two reasons: because Herod persuaded them, and because the star was leading them. Hence, in regard to the first the exhortation is mentioned; secondly, the Magi's zeal in following the star (v. 9). …

Commentary on Matthew ↗

Glossa Ordinaria

According to others, the star was first seen on the day of the nativity, and having accomplished its end, ceased to be. Thus Fulgentius says, "The Boy at His birth created a new star." (Serm. de Epiph.) Though they now knew both time and place, he still would not have them ignorant of the person of the Child, Go, he says, and enquire diligently of the young Child; a commission they would have executed even if he had not commanded it.

Catena Aurea by Aquinas ↗