St. Thomas Aquinas's Appeal to St. John the Baptist as a Benchmark of Spiritual Greatness John Baptist Ku, O.P. When we think of sources of St. Thomas Aquinas's speculative theology, we rightly recall teachings given in Scripture—such as that sin came into the world through one man (Rom 5:12) or that all that the Father has belongs also to the Son (John 16:15)—as well as teachings, based on Scripture, imparted by Church councils or Fathers, such as that Christ is one person with two natures1 or that the human nature of Christ is an instrument of his divinity.2 In the project of faith seeking understanding, these teachings lead expeditiously to distinctions and clarifications concerning person and nature, habit and action, primary and instrumental causality, intellect and will, faith and reason, and the like. However, the saints themselves too serve as a source for Aquinas's speculative theological reflection. Though they admittedly constitute a less abundant source than scriptural, conciliar, or patristic teaching, the saints' contribution to Aquinas's theology merits our attention. For instance, in "Jean-Baptiste: figure du prêcheur chez Thomas d'Aquin," Jean-Pierre Torrell observes that Aquinas's research into the Fathers of the Church for the Catena aurea bore considerable influence on his subsequent works, and Torrell documents how Aquinas's treatment of John the Baptist is a precise case that shows this influence.3 More recent [End Page 1119] scholarship has, fortunately, taken note of the saints' contribution to Aquinas's theology—in the figures of St. Benedict and the virgin martyrs.4 This article will therefore examine St. John the Baptist as just such a source of Aquinas's speculative theology. Aquinas appeals to St. John as a benchmark of spiritual greatness against which to situate other figures: Christ, angels, Mary, apostles, prophets, evangelists, priests, and the people of God. By examining these cases, we will not only observe the Angelic Doctor's appreciation of the saints as our teachers, as examples to be imitated, and as proofs of God's love in transformative grace; we will also witness aspects of the Dominican master's theological method, that is, in his manner of interpreting Scripture and his application of reason to scriptural data to make arguments and draw conclusions.5 For instance, in his treatment of the least in the kingdom of heaven, Scripture will definitively confirm what theological reasoning can determine concerning the knowledge of those with the beatific vision. Furthermore, his exposition on the Blessed Virgin will reveal that he reads the Bible as a whole with one divine author, in support of traditional interpretations.6 However, he is not naive about diverse human authorship and the literal versus the spiritual senses [End Page 1120] of Scripture,7 and his methodology unveils his explicit conviction that Scripture must be the basis of theological claims.8 My presentation will unfold in five sections. After (1) a glance at some of Aquinas's comments on the authority of various sources of theology so as to situate our conversation about the saints as a source of theology, I will review Aquinas's enlistment of John the Baptist as a standard by which to establish: (2) three simple points about Christians and Christ—that all of the articles of faith must be accepted, that prepubescent children can enter religious life, and that Christ's baptism manifests divine power—(3) the superiority of angels to wayfarers, among whom John the Baptist is the greatest, followed by apostles, prophets, and evangelists; (4) the eminence of John the Baptist and a ranking, in order, of God, angels, John the Baptist, prophets, priests, and then God's people; and (5) the holiness of Mary the Mother of God. The Authority of Various Sources of Theology In just a few lines in the Summa theologiae, Aquinas identifies the roles of reason and authority in theology. On one hand, "it is most proper" to theology to offer "proofs from authority," since theology's "principles are known through revelation"—making theological arguments dependent on "the authority of those making the revelation." But on the other hand, theology "also uses human reason, not to...