John Chrysostom

"And the peace of God which passeth all understanding shall guard your hearts and your thoughts in Christ Jesus." What meaneth this? "The peace of God" which He hath wrought toward men, surpasseth all understanding. For who could have expected, who could have hoped, that such good things would have come? They exceed all man's understanding, not his speech alone. …

Homily on Philippians 14 ↗

Theophylact of Ohrid

That is, the peace which God established with mankind surpasses every mind, not only human but also angelic — as if the apostle said: He saved or delivered us in such a way that our mind is unable to comprehend it. For who expected that such blessings would be granted to us and that we would be reconciled with God? He Himself will guard and protect you, so that you would not even think anything evil. Or the apostle speaks of the peace of which the Lord said: "Peace I leave with you" (Jn. 14:27) — it will guard you. …

Commentary on Philippians ↗

Theonas of Alexandria

And never cast off the habit of reading in the Holy Scriptures; for nothing feeds the soul and enriches the mind so well as those sacred studies do. But look to this as the chief gain you are to make by them, that, in all due patience, ye may discharge the duties of your office religiously and piously—that is, in the love of Christ—and despise all transitory objects for the sake of His eternal promises, which in truth surpass all human comprehension and understanding, and shall conduct you into everlasting felicity.

The Epistle of Theonas, Bishop of Alexandria, to Lucianus, the Chief Chamberlain ↗

Thomas Aquinas

Then when he says, and the peace of God... will keep your hearts, he asks that peace descend on the soul now instructed by the things said above. He asks this as though he were entreating. Peace, according to Augustine, is the tranquility of order: for the disturbance of order is the destruction of peace. This tranquility of order is considered from three aspects: first, insofar as it exists in the principle of order, namely, in God: "For there is no authority except from God, and those that exist have been instituted by God. …

Commentary on Philippians ↗

Bonaventure

In the beginning I call upon the first principle, from whom all illuminations descend as from the Father of lights, from whom is every good gift and every perfect gift, namely the eternal Father, through his Son, our Lord Jesus Christ, that by the intercession of the most holy Virgin Mary, mother of the same God and our Lord Jesus Christ, and of blessed Francis, our leader and father, he may give the enlightened eyes of our mind to direct our feet in the way of that peace which surpasses all understanding; which peace our Lord Jesus …

Itinerarium Mentis in Deum, Prologue ↗