Here is what Pius Parsch wrote about this great saint:
St. Hilary was one of those great Christian heroes who poured out their lives laboring and suffering in defense of Christ's divinity. Scarcely had the days of bloody persecution ended (313), when there arose, now within the Church, a most dangerous enemy of another sort, Arianism. The heresy of Arianism denied the divinity of Christ; it was, in fact, hardly more than a form of paganism masquerading as the Christian Gospel. The smoldering strife soon flared into a mighty conflict endangering the whole Church; and its spread was all the more rapid and powerful because emperors, who called themselves Christian, proved its best supporters. Once again countless martyrs sealed in blood their belief in Christ's divinity; and orthodox bishops who voiced opposition were forced into exile amid extreme privations.Here is St. Hilary on Psalm 53:
Among the foremost defenders of the true faith stood Hilary. He belonged to a distinguished family and had received an excellent education. Though a married man, he was made bishop of Poitiers by reason of his exemplary life. It was not long before his valiant defense of the faith precipitated his exile to Phrygia. Here he composed his great work on the Blessed Trinity (in twelve books). It is a vigorous defense of the faith, which, he said, "triumphs when attacked." Finally, after four years he was permitted to return to his native land. He continued his efforts, and through prudence and mildness succeeded in ridding Gaul of Arianism. Because of his edifying and illustrious writings on behalf of the true religion, the Church honors him as one of her doctors.
Here is an example of Hilary's vigorous style: "Now it is time to speak, the time for silence is past. We must expect Christ's return, for the reign of Antichrist has begun. The shepherds must give the warning signals because the hirelings have fled. Let us lay down our lives for the sheep, for brigands have entered the fold and the roaring lion is rampaging about. Be ready for martyrdom! Satan himself is clothed as an angel of light." A favorite motto of St. Hilary was, Ministros veritatis decet vera proferre, "Servants of the truth ought speak the truth."
Hear my prayer, O God, give ear unto the words of my mouth. The obvious thing for the Prophet to say was, O God, hear me. But because he is speaking as the mouthpiece of Him, Who alone knew how to pray, we are given a constantly reiterated demand that prayer shall be heard. The words of St. Paul teach us that no man knows how he ought to pray: For we know not how to pray as we ought . Man in his weakness, therefore, has no right to demand that his prayer shall be heard: for even the teacher of the Gentiles does not know the true object and scope of prayer, and that, after the Lord had given a model.
What we are shown here is the perfect confidence of Him, Who alone sees the Father, Who alone knows the Father, Who alone can pray the whole night through— the Gospel tells us that the Lord continued all night in prayer— Who in the mirror of words has shown us the true image of the deepest of all mysteries in the simple words we use in prayer. And so, in making the demand that His prayer should be heard, he added, in order to teach us that this was the prerogative of His perfect confidence: Give ear unto the words of My mouth.
Now can any man suppose that it is a human confidence which can thus desire that the words of his mouth should be heard? Those words, for instance, in which we express the motions and instincts of the mind, either when anger inflames us, or hatred moves us to slander, or pain to complaint, when flattery makes us fawn, when hope of gain or shame of the truth begets the lie, or resentment over injury, the insult? Was there ever any man at all points so pure and patient in his life as not to be liable to these failings of human instability? He alone could confidently desire this Who did no sin, in Whose mouth was no deceit, Who gave His back to the smiters, Who turned not His cheek from the blow, Who did not resent scorn and spitting, Who never crossed the will of Him, to Whose Will ordering it all He gave in all points glad obedience.