Giles of Viterbo (1469–1532), cardinal of the Roman Catholic Church during the High Renaissance, was not merely a scholar influenced by the humanism and renewed Platonism of his day but a phil-Hellene according to various associations of Hellenism ranging from literary to political, ancient to modern. He embraced Hellenism in its many senses despite his belonging to the generation born after the fall of Constantinople. This is significant, for although Giles's interest in ancient Greek language and letters is generally acknowledged, insufficient scholarly attention has been paid to Giles's inclusive interest in Byzantine Hellenism and Orthodox Christian doctrine.

The English cleric John Colet (ca. 1467–1519) composed a commentary on the Ecclesiastical Hierarchy of Dionysius, the legendary disciple of Saint Paul. Colet approached the Dionysian text not as an artifact belonging to another time and place but as a living document, much as he approached St. Paul's Letters in his commentaries. His goal was to critique lapses in ecclesiastical virtue and to instill a spirit of personal and institutional reform by comparing the sacramental and hierarchical practices of the sixth-century Dionysian Church with those of his Church in England. This essay suggests a new path to understanding the distinctiveness of reforms advocated by Colet. By referring to specific elements, including the practices of baptism and the eucharist and the nature of the office of bishop, Colet was able, via Dionysius, to reveal alternative possibilities of reform by adopting patristic and, although perhaps unwittingly, Eastern Orthodox thought and practice. What has not been appreciated thus far is that Colet's Ecclesiastical Hierarchy produces for a Latin readership in England a neo-Patristic blueprint that resembles in significant details the living ecclesiology of the Christian East, which was coming to light in the West through the humanist restoration of patristic texts and debates among scholars in Italy over Union and Conciliarism.

Giles of Viterbo's early sixteenth-century commentary on Peter Lombard's Libri sententiarum includes a discussion of the controversial Western doctrine of the procession of the Holy Spirit from the Father and the Son (Filioque) in its regular place at distinction 11 of book 1. In treating this issue Giles remained true to his aim of producing a commentary ‘according to the mind of Plato’ (ad mentem Platonis). Giles had access to the dialogues of Plato but only limited access to original texts of the Greek Fathers. Nevertheless, he reviewed the Filioque controversy in a manner which respects the sententia Graecorum, even disagreeing with a line of argumentation championed by scholastic supporters of the Augustinian tradition, including Thomas Aquinas, over the related question of whether it should be said that there is one spirator or plural spiratores. Giles' conciliatory position owes much to his intellectual environment, which fostered a renewed admiration for Hellenism and classical humanism. Working largely without benefit of the emerging rediscovery of Eastern patristic theology Giles nevertheless reassesses the arguments for and against the Filioque which he received from the Latin scholastic tradition, seeking, as he does throughout his commentary, what is true on both sides of apparently divergent teachings on divine mystery.

Egidio of Viterbo's Sentences-Commentary ad mentem Platonis blends scholastic theological argumentation with the poetic theology of Ficinian Platonism. This essay examines Egidio's application of myths drawn mainly from the Platonic dialogues to residual questions, after he successfully addressed the question of divine generation. The allusions do not just embellish, but embody the fundamental theological truth as revealed in scripture and tradition. Egidio incorporates philosophical humanism and the literary sensibilities of his age into the Sentences- Commentary genre.

From the earliest Christian centuries, the doctrine of divine generation brought forth an abundant and controversial literature. From the Father-Son terminology in the Old and New Testaments, to the Gospel of John's repeated naming of Christ as, unigenitus a patre, only begotten of the Father, to the Nicene-Constantinopolitan Creed's proclamation of “God from God, Light from Light, True God from True God, begotten not made, of one essence with the Father,” to the Council of Chalcedon's proclamation that the divine Son was “begotten before all ages of the Father according to the Godhead,” the articulation was vast and prolific. Further, the formula that emerged victorious and enduring in late antiquity still challenged and urged later theologians to write treatises on the doctrine for centuries to come. That the Father is presented as uniquely the Father of the Son, and the Son uniquely the Son of the Father is a dogmatic formula based on revelation, but how God begets God without either making himself or another God was a question formulated to approach theologically the complexities of the divine Trinity, particularly the relation among the three distinct divine persons in one divine nature.

The theology of the Holy Spirit waited through the early Christian centuries until the main doctrines regarding the Trinity and the person of Christ had been forged. Even then pneumatology was introduced ‘by the back door’, in Theodore Campbell's phrase, that of how the Son was placed in the Father, Son and Spirit confession. While prayers to the Spirit were not lacking in the earliest liturgies, still, at Nicea the doctrine ‘had been disposed of in lapidary brevity’, as Jaroslav Pelikan has described the credal line, ‘and we believe in the Holy Spirit’. ‘Nor does there seem to have been a single treatise dealing specifically with the person of the Spirit composed before the second half of the fourth century’. After Nicea, however, controversy concerning the Spirit erupted ‘with a vengeance’, producing the same kind of energy that had accompanied the Christological debates. Pneumatomachi, Tropici, and Macedonians, though losers in the fight for orthodox doctrine on the Spirit's nature, had mounted formidable campaigns, as Arians had done over the relationship of Christ to the Father. But disagreement over the Spirit had an even greater impact than Arian opposition in that the filioque remains a principal difference between the Catholic and Orthodox, and now Catholic and Anglican, creeds.