Hanson spends a lot of time demonstrating that St. Patrick was not influenced by the Patristic theology and disputes on the Continent, but rather had a more evangelical, biblical, though still Catholic faith, acquired in that out-of-the-way backwater, sub-Roman Britain. This is Very Good to Hanson, because it saves him from being influenced by Patristic scripture interpretation. Rather, St. Patrick interprets Scripture in its plain sense, like a good Protestant, or Antiochene:
In the first place, his biblical interpretation is remarkably sound and sensible. When one has read the far-fetched allegorizing, the determined identification in the pages of the Bible of a complex and uniform system of thought which exists in the writer's fantasy but not in the Bible, the learned nonsense and high-flown imaginary constructions which appear in the biblical interpretation of the leading theologians (both Eastern and Western) of the fourth and fifth centuries--of Hilary and Ambrose and Jerome, or Athanasius and Basil and the two Gregories, of Eusebius of Caesarea and Epiphanius and Didymus--one turns with relief to the straightforward and simple use which Patrick makes of the Bible. He has the virtues of his deficiency. He is not well educated enough, he has not enough learning to indulge in the sophisticated silliness of much Patristic hermeneutics. He goes straight to the heart of the biblical message, to the promises of God in the Old Testament, to the redemption brought by Christ in the New. God's self-giving and love, God's demand of holiness and faith, God's trustworthiness and providence, the presence of the Holy Spirit in the hearts of believers, these are his themes; he has no difficulty in finding these in the pages of the Bible, and does not look further.Such prejudice was common even among Catholic biblical exegetes in the period between 1950 and 1990. In fact, they are still there among many of them. Fortunately there is a renewed interest in recovering a disciplined version of Patristic allegory, in no little part due to the monumental work of Henri de Lubac in Medieval Exegesis. More recently Robert Louis Wilken has done much to recover the power of Patristic allegory to get at "the heart of the biblical message." Also, the St. Paul Center of Biblical Theology of Scott Hahn works closely in this area. Even Protestants are enthusiastic, such as the editors and readers of the Ancient Christian Commentary on Scripture, edited by Thomas C. Oden and Christopher A. Hall (Intervarsity Press). (If you know of other such efforts, please put them in the comments; I'll add them to this post).
What St. Thomas says is:
The author of Holy Writ is God, in whose power it is to signify His meaning, not by words only (as man also can do), but also by things themselves. So, whereas in every other science things are signified by words, this science has the property, that the things signified by the words have themselves also a signification. Therefore that first signification whereby words signify things belongs to the first sense, the historical or literal. That signification whereby things signified by words have themselves also a signification is called the spiritual sense, which is based on the literal, and presupposes it.
The basis of spiritual exegesis is that the meaning of things is fuller than their terrestrial significance. God has included all temporal reality in a greater "plan." Temporal realities not only relate to other temporal realities, but, by God's design and intention, relate to the supernatural, eternal reality. A temporal reality not only represents itself, but is drawn up into and "signifies" the invisible, which is more fully real and only fully know and understood by God. This is the famous "sacramental principle" of contemporary articulations of Catholic principles. Since God knows more about these connections than the sacred authors, then the meaning of the text can and does mean more than the intended meaning of the sacred authors.
This is especially relevant for the Old Testament, whose authors did not have the benefit of knowledge of Christ and the outpouring of the pentecostal Spirit. Yet, even the New Testament texts may have a sense that is only known fully when we achieve the glory of the Resurrection.:
Now this spiritual sense has a threefold division. For as the Apostle says (Hebrews 10:1) the Old Law is a figure of the New Law, and Dionysius says (Coel. Hier. i) "the New Law itself is a figure of future glory." Again, in the New Law, whatever our Head has done is a type of what we ought to do. Therefore, so far as the things of the Old Law signify the things of the New Law, there is the allegorical sense; so far as the things done in Christ, or so far as the things which signify Christ, are types of what we ought to do, there is the moral sense. But so far as they signify what relates to eternal glory, there is the anagogical sense. Since the literal sense is that which the author intends, and since the author of Holy Writ is God, Who by one act comprehends all things by His intellect, it is not unfitting, as Augustine says (Confess. xii), if, even according to the literal sense, one word in Holy Writ should have several senses.