In its formlessness and potentiality, prime matter is a problematic entity of medieval metaphysics and its ontological limitations drastically affect human possibility of conceiving it. In this article, I analyse three influential strategies elaborated to justify an epistemic access to prime matter. They are incidental perception, negative abstraction, and analogy. Through a systematic and historical analysis of these procedures, the article shows the richness of interpretations and theoretical stakes implied by the conundrum of how prime matter can be known by (...) human beings. In particular, the reasons behind the later medieval acceptance of analogy as the main way to unveil prime matter become clearer by pointing out the correlation between the ontological and epistemological levels of the medieval examination of prime matter. (shrink)