 Apart from the permanent creative tension between theology and philosophy, medieval thought, after the rediscovery of Aristotle’s Metaphysics in the twelfth century inspired by Arabic scholars, can be characterized as an elaborate and subtle interpretation and development of, mainly Aristotelian, classical theory. Reflection on the notion of informatio is taken up, under influence of Avicenna, by thinkers like Aquinas (1225–1274 CE) and Duns Scotus (1265/66–1308 CE). When Aquinas discusses the question whether angels can interact with matter he refers to the Aristotelian doctrine of hylomorphism (i.e., the theory that substance consists of matter (hylo (wood), matter) and form (morphè)). Here Aquinas translates this as the in-formation of matter (informatio materiae) (Summa Theologiae, 1a 110 2; Capurro 2009). Duns Scotus refers to informatio in the technical sense when he discusses Augustine’s theory of vision in De Trinitate, XI Cap 2 par 3 (Duns Scotus, 1639, “De imagine”, Ordinatio, I, d.3, p.3).