St. Hilary has made the assertion that the person speaking in the First Psalm is a prophet. He now moves on to whom the prophet is speaking:
And as he says this we must enquire concerning what man we are to understand him to be speaking. He says: “Happy is the man who hath not walked in the counsel of the ungodly nor stood in the way of sinners, and hath not sat in the seat of pestilence. But his will hath been in the Law of the Lord, and in His Law will he meditate day and night. And he shall be like a tree planted by the rills of water, that will yield its fruit in its own season. His leaf also shall not wither, and all things, whatsoever he shall do, shall prosper.” I have discovered, either from personal conversation or from their letters and writings, that the opinion of many men about this Psalm is, that we ought to understand it to be a description of our Lord Jesus Christ, and that it is His happiness which is extolled in the verses following. But this interpretation is wrong both in method and reasoning, though doubtless it is inspired by a pious tendency of thought, since the whole of the Psalter is to be referred to Him: the time and place in His life to which this passage refers must be ascertained by the sound method of knowledge guided by reason.
So, St. Hilary argues that the Psalm is neither Christ speaking nor is it speaking to or about Christ; however, note that “the whole Psalter is to be referred to Him.” It does not matter that Christ is not speaking in the First Psalm, or that it is not being spoken to Christ or directly about Christ, the First Psalm will still reveal something about Christ to us.
Note also, that (unlike so many modern characterizations to the contrary) the path that St. Hilary intends to take in order to understand this revelation is paved by sound method of knowledge and reason. One of the first things that always strikes me about the men the Fathers of the Church were, is that they are nothing if not reasonable. One of the reasons I go to the trouble during this time of year of reading a Father and wrestling with what he has to say is specifically to get know the man.
The more one knows about a person, the harder it is to disregard that person and what that person says and does (good or ill). The more I read the Fathers and share what I know about the Fathers, the harder it is for me (and hopefully others) to disregard what they say as either unimportant or irrelevant to the age we live in.
As one can already see, it does not matter that St. Hilary wrote these words almost 1700 years ago. What he says about the First Psalm is just as relevant today as it was in 4th century.