In the prologue to his commentary on the book of the prophet Isaiah, St. Thomas Aquinas writes: “Now the subject matter of this book is principally the appearing of the Son of God, hence in the Church this book is read in the time of Advent.” As St. Thomas points out, most Christians have the words of Isaiah ringing in their ears at this time of year: “a virgin shall conceive and bear a son”; “for unto us a child is born”; “a rod shall come forth from the root of Jesse”; “a voice cries out in the wilderness.”
So the Aquinas Institute has decided to do something we have never done before: rather than wait until hardcover books are all printed and ready for sale, we have released Aquinas’s Expositio super Isaiam ad Litteram online today—the first time this work has ever appeared in English. Dr. Joshua Madden, who wrote his dissertation on the Isaiah commentary at Ave Maria University, has provided a crisp translation with helpful footnotes.
This commentary was St. Thomas’s earliest theological work, predating even his commentary on the Sentences. He composed it, not as a master lecturing to graduate students, but as a graduate student lecturing undergraduates cursorie, offering a rapid tour of the plain sense of the Bible.
Cursory though it may be, raw and sometimes rushed, the Expositio super Isaiam ad Litteram remains an astonishing work. Even without the team of research assistants he would later enjoy, St. Thomas quotes St. Jerome, St. Augustine, St. Ambrose, St. Gregory, St. Bernard, and others, as well as the standard medieval glosses. Despite such roots in the tradition, certain of his comments were so boldly contrary to opinions of the day that later readers doubted whether this exposition of Isaiah could really be from the Angelic Doctor. All doubts were erased, however, when a partial autograph copy of the manuscript was found in 1844 containing the commentary on chapters 34 to 50 in the saint’s own famously illegible hand.
Why should you read St. Thomas’s commentary on Isaiah? We can think of at least three reasons:
1. St. Thomas highlights the literary and structural qualities of the text.
Noting in his preface that Isaiah, more than any other prophet, employs the most “beautiful and perfectly chosen figures” to convey his message, St. Thomas remains attuned to this aspect of the text when it appears. See for example his measured yet profound comment on harlot’s song in Isaiah 23:15. Instead of flattening the text into a theological treatise, St. Thomas allows us to feel the weight of the metaphor, drawing out the affective imagery of a forgotten woman and finally drawing the parallel between the scorned lover and the city of Tyre. At the same time, St. Thomas pays careful attention to the organization of the text, dividing and subdividing all the way down to particular phrases. Click here for Aquinas’s general outline of the work.
2. St. Thomas allows Scripture to comment on Scripture.
At points, the reader almost forgets St. Thomas’s presence as a commentator. Following key words and thematic ties, he weaves together verse after verse from other books of Scripture and from other passages in Isaiah to illuminate the text at hand, allowing his authorial voice to give way to the voice of Scripture itself. For example, meditating on the phrase “from the sole of the foot even to the head” in Isaiah 1:6, St. Thomas recalls Isaiah 56:11, Wisdom 7:6, Leviticus 10:19, Psalm 99:2, and Psalm 13:3, illustrating the illness of Israel at every level of society.
3. St. Thomas’s commentary is theological.
Never separating textual interpretation from the consideration of reality, St. Thomas pauses to discuss theological issues as they arise. For example, commenting on the first word of the entire book, namely “vision,” he explores the nature of prophecy in general and how a prophetic “vision” relates to the broader category of “visions,” including the “beatific vision.” When he comes to the messianic prophecy of Isaiah 11, the traditional source-text for the Gifts of the Holy Spirit, St. Thomas pauses to explain the nature of these gifts, their number and order of the Gifts, how Christ possessed them in a unique way, and why they are attributed to the Holy Spirit—all within the compass of a couple of pages. Faith and exegesis go hand in hand throughout the Expositio.
And with that, we return to the reason for releasing this precious text now, during the season of Advent. St. Thomas brings us not only closer to the literary text that gives these weeks their distinctive sound, but also to the reality we await: the coming of our Lord Jesus Christ.
 Cf. Leonine edition, vol. 28, 20*.
 Torrell, St. Thomas Aquinas: Vol. 1, The Person and His Work, 337.
 Cf. Preface to the Leonine edition, 3-4; see also Torrell, St. Thomas Aquinas: Volume 1, The Person and His Work. Translated by Robert Royal (Washington D.C.: The Catholic University of America Press, 1996), 27-28.
 Cf. Leonine edition, vol. 28, 14*-15*.