Thomas de Vio (Cardinal Cajetan) is too often remembered only for his failure to convince Martin Luther to remain in obedience to the established church. However, he was more creative and intellectually engaged than that. His treatment of Thomism, which is best found in his commentary on the Summa theologiae, was more than mere repetition of the Angelic Doctor's teachings. He felt free to disagree with the Thomistic orthodoxy of his day. This very creativity drew the ire of Sylvester Prierias and other fellow Dominicans, whose idea of Thomism was narrower. Similarly, Cajetan embarked in the 1520s on a sustained engagement with biblical texts. His motivation, as O'Connor rightly argues, went beyond the polemics exchanged between Luther and his foes. His motivation included the renewal of Christianity, and he did not hesitate to retranslate and comment on the biblical texts. Cardinal Cajetan treated most of the New Testament and large parts of the Old. In this he drew creatively on the original languages, which is exactly what he had done in interpreting Aristotle. When he died in 1534 he left behind the beginning of a treatment of the text of Isaiah. In between, he wrote answers to the Lutherans and treated the marital problems of Henry VIII.

Cajetan's exegesis led him to criticize the Latin Vulgate without abandoning it. Moreover, his emphasis was on literal interpretation of scripture, rather than pursuing the various spiritual senses past exegetes had expounded. This, in turn, put him outside the mainstream of Catholic biblical scholarship that flourished in succeeding centuries. That did not mean a divorce from papal authority, the ecclesial context, or a hard line of emphasis on sola scriptura, typical of much Protestant scholarship in his time. Instead, as O'Connor notes, Cajetan paid proper respect to the patristic consensus when seeking meaning in the sacred texts and providing material for preachers and pastors. An interesting aspect of the cardinal's exegesis, as the author highlights it, was a willingness to admit the limits of exegesis, not seeking clever ways to answer unanswerable questions.

O'Connor gives very useful attention to how broad and deep was Cajetan's sense of the letter. It was not a mere springboard to further speculation. Instead it involved literary tools, seeking understanding of the human contribution to the transmission of revelation. Languages and literary devices like metaphor fell within the study of the literal sense. All other interpretations were to be based on that foundation. This wider sense of the letter was, as the author notes, a very creative engagement. Polemic was not excluded, but it too had to be based on the letter.

O'Connor's book can be read with profit not only for its engagement with the subject's biblical labors but for the wider reading of his writings. Cajetan brought his exegetical tools to the discussion of issues like the immortality of the soul, a hot topic in the time of the Fifth Lateran Council and one that remains of interest for the history of Renaissance philosophy.