Toward the Genesis of the Kristeller Thesis of Renaissance Humanism. Four Bibliographical Notes
Monfasani, John, Renaissance Quarterly
Paul Oskar Kristeller's interpretation of Renaissance humanism as a "characteristic phase in what may be called the rhetorical tradition in Western culture"  has exercised an enormous influence on Renaissance studies. What I wish to do here is to call attention a group of works that affected in one way or another Kristeller's thinking about the Renaissance in general and about Renaissance humanism in particular.
Paul Oskar Kristeller first enunciated his thesis on the nature and origins of Renaissance humanism five years after he came to America from Italy -- in a lecture, to be precise, at Connecticut College on 9 March 1944.  Among other points, Kristeller showed that the word humanist began as. a vernacular term in Italian school culture (i. e., humanista) and that it referred to the teacher of a specific set of subjects. Kristeller's friend Augusto Campana had independently and nearly contemporaneously made the same discovery.  But neither Campana nor anyone else had traced the origins of Renaissance humanism back to its medieval Italian rhetorical roots and the French rhetorical commentary tradition.  Kristeller's knowledge of the texts of the Italian Renaissance was extraordinary; but so too was that of Jakob Burckhardt, Georg Voigt, Remigio Sabbadini, Vittorio Rossi, Giuseppe Saitta, and Eugenio Garin, to mention only some of the major commentators on Renaissance humanism predating or contemporary to Kristeller in the mid-1940s. Kristeller was different because he brought to the task a distinct preparation that separated him from other commentators. There is no accounting for originality, but knowledge of Kristeller's training helps to explain elements of his theory.
1. HANS VON ARNIM'S DIO VON PRUSA
Kristeller received his doctorate from the University of Heidelberg in 1928, qualifying as an expert in ancient philosophy with a dissertation on Plotinus.  He then returned to Berlin to gain professional competence in classical philology, There he enjoyed the tuition of a breathtakingly distinguished group of teachers. He participated in the seminars of Eduard Norden and Werner Jaeger, and attended the lectures of Ulrich von Wilamowitz-Mollendorff, Paul Maas, Eduard Meyer, Wilhelm Schulze, Friedrich Solmsen, and Richard Walzer.  Norden had a large knowledge of classical rhetoric; indeed, his famous Die Antike Kunstprosa (1898) would not have been possible without such a knowledge. Jaeger had made his reputation by his work on Aristotle, but he too had an interest in the antique rhetorical tradition. 
During his years in Berlin, Kristeller wrote seminar papers on Cicero's Orator and his oration Pro Murena, and passed his state board examination with a thesis on Pericles's speech at the end of book 1 of Thucydides.  Therefore, it is inconceivable that he did not read -- at this time, if not earlier -- Hans von Arnim's Leben und Werke des Dio von Prusa, mit einer Einleitung: Sophistik, Rhetorik, Philosophie in ihrem Kampf um die Jugendbildung (The Life and Writings of Dio of Prusa, with an Introduction: Sophistic, Rhetoric, Philosophy in Their Battle over the Education of Youth). Dio "Chrysosrom" of Prusa was a notable figure of the Second Sophistic during the Roman Empire. Arnim's Dio von Prusa is the first authority on antique rhetoric Krisreller cited in his Martin Classical Lectures of 1954, the definitive statement of his theory on Renaissance humanism.  Arnim would have been well known to Kristeller, in any case, from his Stoicorum Veterum Fragmenta, which was then as now indispensable to studen ts of ancient philosophy What made Dio von Prusa especially valuable from the perspective of someone interested in philosophy was its lengthy first part, announced in the book's subtitle, where Arnim traced the competition between rhetoric and philosophy from the fifth century B.C. to Dio's time in the second century A.D.  Armin made the broad sweep of antiquity his focus rather than an individual period and showed that these two educational cultures more often than not peacebly co-existed over the centuries despite celebrated moments when they broke out in open warfare against each other. …