The above photograph is the very handwriting of St Thomas Aquinas, his Literal Exposition on Isaiah to be exact. If you click on it for a closer view, you will see just how indecipherable his penmanship is--if we can even call it that! Most of his writings were either dictated to secretaries or reported as lecture notes by his students.
As I explained elsewhere, the study of the Bible in the Middle Ages was a much weightier affair than it is today; in fact, St Thomas all but uses the terms 'Scripture' and 'doctrine' as though they were synonyms (S.th. 1a, q. 1, art. 7 & art. 8). In fact, his contemporary, St Bonaventure, goes so far as to begin his theological handbook by speaking of "Scripture, which is to say theology" (Breviloquium, I, 1). Fr Yves Congar OP has gone so far as to say that Catholic theology can, in fact, make use of the Protestant battle-cry of "the Bible only!" but in a qualified sense: "We can admit sola Scriptura in the sense of a material sufficiency of canonical Scripture. This means that Scripture contains, in one way or another, all truths necessary for salvation." Ever since the Council of Trent, there has been a knee-jerk reaction to the question of authority in doctrine by speaking of "Bible" and "Tradition." While that is true, it would have sounded strange to St Thomas' ears, or to any mediaeval theologian for that matter. Part of why it would have sounded strange to them would be because they would likely have replied, "When are we not doing Scripture?" Indeed, as any historian of the Middle Ages will tell you, mediaeval culture was, by necessity, a Biblical culture. Yes, it is fact difficult for post-Henry VIII Anglophones to come to grips with, but Beryl Smalley has definitively settled that for us in her groundbreadking The Study of the Bible in the Middle Ages (South Bend, University of Notre Dame Press, 1989).
St Thomas spent his early years in what we might today call a boarding school, except for him, he wore the habit of a Benedictine monk (he was an oblate), shared in their liturgical and fraternal life, and studied at their school attached to the great abbey of Monte Cassino. The bulk of the time was taken up in consuming the Bible in large quantities: At the celebration of the Divine Office, at Mass, during meals when it was read (along with other texts), and in private reading during lectio divina, the hallmark of Benedictine spirituality. The mediaevals read Scripture in a somewhat obtuse way compared to our own age, with layers and levels of meaning: Beyond the literal, to the spiritual sense.
When St Thomas became a Dominican friar in April of 1244, his method of reading Scripture changed considerably. During the years of 1239-1244, he was a student at the University of Naples studying the liberal arts--principally grammar, logic, and rhetoric. Centuries prior, both St Augustine and St Cassiodorus defended the study of the "secular" liberal arts as a preparation for Bible reading; Charlemagne later made it standard curriculum in the cathedral and monastic schools. Since St Thomas was a Friar Preacher, it was important for him (and his brothers) to have a firm grip on the word of God in such a way that when it was presented to the heretics, say, or even to Catholic believers, it would be quickly grasped and understood, and that meant focusing on the literal sense. It is easy to quarrel over the interpretation of symbols and the like, but when we read the Sacred Text as text, we paint ourselves into a corner with the plain meaning of what's written. And the tool for that was, principally, grammar.
In fact, St Thomas begins his great Summa theologiae by speaking of the literal sense as the foundation of "sacred doctrine" (the word "theology" was only beginning to gain the sense it has today). And that is why the title of his commentary on the prophet Isaiah is called Literal Exposition on Isaiah--because he focuses on the literary sense of what this "Fifth Evangelist" (as St Jerome called Isaiah) wrote. When we say "literary," however, we don't mean literalistic, as though God wore a long wedding-dress (Is 6:1) or has a cloud for an automobile (Is 19:1). In fact, the "literal sense" has three levels of meaning:
These three--history, etiology, analogy--are grouped under the literal sense. For it is called history, as Augustine expounds (Epis. 48), whenever anything is simply related; it is called etiology when its cause is assigned, as when Our Lord gave the reason why Moses allowed the putting away of wives--namely, on account of the hardness of men's hearts; it is called analogy whenever the truth of one text of Scripture is shown not to contradict the truth of another (S.th., 1a, q. 10, art. 1, ad 2).
That being said, St Thomas employed the full gambit of the literal sense in his Literal Exposition on Isaiah.
We are looking at the years 1251 as the earliest possible start of this commentary, and 1253 as the latest possible completion; moreover, it would have been a two-year project sometime within these dates, during which Thomas gave a brief and rapid 'exposition' on the text of Isaiah as part of his training to become a theologian--except the proper title was Magister in Sacra Pagina, "Master of the Sacred Page." After finishing his B.A. in the liberal arts (hence "Bachelor of Arts"--baccalaureus artium), his training in sacred doctrine began at the University of Cologne under St Albert the Great with two additional Bachelors' degree: A Bachelor of the Bible (baccalaureus Biblicus), then a Bachelor of the Sentences (baccalaureus Sententiarum). Each required something like a Senior's Thesis, except as a Biblical Bachelor, they--including St Thomas--had to lecture on a book of the Bible and give a rapid commentary on it. This is what St Thomas' Literal Exposition on Isaiah was all about.
It appears as though he began his commentary on Isaiah in Cologne and finished it in Paris, though some scholars think it was done entirely in Paris.
As I mentioned earlier, St Jerome considered Isaiah, though it is an Old Testament book, "the Fifth Gospel"; it is the most oft-quoted text in the New Testament. Having sixty-six books, commenting on Isaiah was no small feat for a twentysomething! But he already had long years of ferment to prepare him for such a task--his monastic experience at Monte Cassino, his study of of the liberal arts as well as Aristotle at Naples, and his tutelage under the brilliant polymath Albert the Great.
And it is a marvel to read.