The texts edited in this volume deal with angelology and anthropology, and particularly with the nature and the functions of immaterial substances like angels and the human rational soul. Marchia discusses such controversial issues as universal hylomorphism, i.e., whether angels and the rational soul are composed of both matter and form (q. 13), the immortality of the soul (qq. 18-19), and the nature and the object of the intellect and will (qq. 20, 21), as well as the functionality of the angelic intellect - whether angels understand through discursive reasoning (q. 23), and how they can speak with each other (q. 26). The problematic nature of the relationship between the material and the immaterial is approached through asking whether an angel can produce a material object (q. 22) and whether a material object can be the source of an angel's understanding of that object (q. 25). A particularly interesting treatment concerns how angels, immaterial substances, can be in a place (q. 16); this treatment includes Marchia's attempt to provide a physical theory explaining why an angel cannot move over some distance instantaneously.
Throughout these fifteen questions, Marchia challenges the ideas of some of the best minds of the later Middle Ages, not only major figures of the thirteenth century like Thomas Aquinas, Bonaventure, Henry of Ghent, and Giles of Rome but also fourteenth-century authors like John Duns Scotus, Hervaeus Natalis, Walter Burley, and Peter Auriol.