Aquinas’ Most Frequently Referenced Greek, Roman, Christian, Islamic, and Jewish Philosophers with a Study of Avicenna

This quantitative analysis of direct references to the two most frequently cited Greek, Roman, Christian, Islamic, and Jewish philosophers within Aquinas’ opus, with a detailed examination of Avicenna, addressed a gap in the systematic enumeration of sources using a three-tiered methodology, which included documentation of Aquinas’ direct citations from Leonina, cross-checked with Index Thomisticus, and statistically validated. The findings demonstrated dominance of Christian Augustinus and Dionysius and Greek Aristoteles and Plato, with the highest concentrations in Summa Theologiæ and Expositio Aristotelis, respectively, while affirming Islamic philosophy’s secondary influence through Averroes and Avicenna. Roman and Jewish sources had the fewest references. A near-perfect correlation between the Leonina and Index Thomisticus datasets was established. This study’s data-driven approach to Thomistic philosophy bridged traditional textual scholarship with digital humanities and by documenting Aquinas’ direct sources, refined our understanding of the divergent philosophical traditions’ influences on Aquinas’ philosophical and theological synthesis. Its originality and contribution lie in establishing a consistent methodology for documenting direct references to multiple sources across a complete philosophical opus and facilitating replicable textual and computational analysis in Thomistic, medieval, and manuscript studies.