Claiming that every corporeal thing is made of matter and form, hylomorphism is a cornerstone of premodern metaphysics. Originated from Aristotle’s works, hylomorphism soon exceeded the boundaries of Aristotle’s speculative framework. Thought of as an alternative to Plato’s transcendentalism, for centuries the Latin philosophical tradition was marked by a syncretic approach to both theories. Application of the hylomorphic device led to the formulation of elegant metaphysical theories that expanded on Aristotle’s original stances. Among these doctrinal developments, ancient and medieval philosophers have often maintained that the universe was shaped out of an original, prime matter (prōtē hylē, al-hayūlā al-’ūlā, materia prima) corresponding to the potential and unqualified substrate of (corporeal) existence.

‘The Elusive Substrate’ aims at disentangling the richness of metaphysical theories of original/prime matter that have been produced in the centuries-long philosophical debate about this concept. Focussing on the Latin tradition, the congress reconstructs the main tenets of the history of prime matter by considering how philosophers envisioned the basic ontological constitution of the universe. Such examination will be centred on nine historical phases. These are sections of the Latin debate that are characterised by doctrinal peculiarities, authoritative references, and specificities of problems to be addressed. Each phase will be engaged through the examination of three case-studies. Through their insights, the congress will examine the history of prime matter from a unitary perspective enriched by a plurality of philosophical doctrines and methodological approaches.

The point of departure of this speculative journey is ancient Rome. The first panel of the congress discusses three thinkers who endorsed radically different ontologies of matter: Lucretius, Cicero, and Galen. Although their influence on the long Middle Ages has been divergent, intermittent and, sometimes, only mediated, the reflections of these three thinkers played a foundational role for the Latin debate on the material substrate. With the second panel, the discussion moves to the late-antique debate to examine the theories elaborated by Gregory of Nyssa, Numenius, Calcidius, and Augustine. These authors shaped many central coordinates of the medieval discussion on the original substrate of the universe both directly (in the case of Calcidius and Augustine) and indirectly (Gregory and Numenius).

The first six centuries of the medieval debate were characterised by the absence of Aristotle’s physical and metaphysical works. Few exceptions aside, a proper discussion of ‘matter’ and ‘form’ only started in the 12th century and in strict connection to the Greek- and Arabic-to-Latin translation movements. By considering the cases of William of Conches, Gilbert of Poitiers, and Hermann of Carinthia, the third panel engages with the ‘12th-century Renaissance’. In different ways, these philosophers contributed to opening new doctrinal perspectives grounded on Platonic, Hermetic, and Aristotelian works, preluding to the ‘return’ of Aristotle. Such return, however, was profoundly mediated by Islamicate philosophy. The fourth panel of the congress is focused on understanding how Islamicate philosophy and the theories of matter developed in that tradition provided the interpretative coordinates to navigate (and re-define) Aristotle’s hylomorphism both directly and indirectly. This is achieved by an examination of the theories of matter elaborated by three philosophers in particular: al-Kindi, Avicenna, and Averroes

The 13th-century debate expanded on how to consider prime matter in metaphysics and natural philosophy. This speculative effort resulted in a great number of controversies, marked by the elaboration of opposite hylomorphic models. Richard Rufus of Cornwall, Roger Bacon, and Thomas Aquinas are probably the best examples of this fragmented discussion of the ontological constitution of the universe. Their theories are analysed in the fifth panel. The sixth panel will then focus on the discussion immediately following Bacon and Aquinas. After Scotus, the debate gradually became more consistent in assuming some basic features characterising prime matter. Increased ontological thickness and the consideration of matter as a bodily feature shifted much of the discussion to focussing on the ontological constitution of physical substances. As a consequence, prime matter became a fundamental element of interconnection – and then, friction – between metaphysical and natural analyses of the universe.

Disciplinarily and methodological frictions characterised the last decades of the Latin Middle Ages. By focussing on three eminent cases –Wycliff, Nicholas of Cusa, and Leo the Hebrew– the seventh panel scrutinizes how Platonic tendencies and recurring ontological problems contributed to a process of reinterpretation, emendation, and detachment from Aristotelian hylomorphism. In opposite ways, Pietro Pomponazzi, Francisco Suárez, and Francis Bacon marked the end of the long medieval debate on prime matter and hylomorphism. Their doctrines are examined in the eighth panel of the congress. The discussion about the original matter of the universe would not cease to fascinate generations of philosophers and scientists. Yet its main tenets and speculative coordinates irremediably changed with the passage to the Early Modernity.

Crucially, Aristotelian hylomorphism had some remarkable influence also on non-European philosophical traditions. While the end of the Middle Ages marked a re-dimensioning of Aristotelianism in Europe, the movement of people and ideas characterising Early Modernity allowed texts and doctrines to spread outside the boundaries of Europe and the Mediterranean Basin. The session explores two fundamental venues of such cross-pollination: China and Latin America. How did the Jesuit engage with hylomorphism and prime matter in their Chinese translations of texts proceeding from the Aristotelian tradition (e.g., the Coimbra commentaries)? How were these doctrines rendered in order to fit with the long-lasting tradition of Chinese philosophy? And finally, what remains of the debate of prime matter in the commentaries on Aristotle made in Latin America during the 17th and 18th centuries? These questions will be discussed in the ninth panel of the congress.

May to July 2022
Phase two will unfold during nine meetings to be held in May and July 2022. Each meeting will discuss the respondent’s comment on the papers of their panels (made available to all participants). In their comments, respondents are encouraged to address the papers, both in themselves and in connection to the other papers of the (same) panel. Respondents’ comments (20 to 30 minutes) will be followed by a general discussion of each paper.

Programme updates
Meeting times will be established in accordance with the panelists’ locations and time zones. Details will be communicated in advance via email and on the website. 

All speakers and respondents are invited to participate in the meetings. Further attendees are required to contact the organiser by email ( 

Recordings of the sessions are available for participants who were unable to attend the session. Please, note that the sessions are work-in-progress discussions of papers. The recordings and their contents should be treated accordingly, i.e., as instruments to follow the ongoing discussion of The Elusive Substrate instead of lectures on a specific topic. If you have any inputs, feel free to contact speakers, chairs, and organiser at any time.


Speakers: Daryn Lehoux, John Wynne, Peter N. Singer
Chair: Charles Brittain



Speakers: Anna Marmodoro, Gretchen Reydams-Schils, Enrico Moro
Chair: John Magee


Speakers: Clelia Crialesi, Magdalena Bieniak, Charles Burnett
Chair: John Marenbon


Speakers: Emma Gannagé, Andreas Lammer, Matteo Di Giovanni
Chair: Peter Adamson


Speakers: Neil Lewis, Jeffrey Brower, Nicola Polloni
Chair: Rega Wood