Robert Kilwardby on the Human Soul is the first in-depth study on Kilwardby's contribution to the thirteenth-century philosophical and theological debate on the nature of the soul and its relation with the body. The book examines his innovative approach to the plurality of substantial forms in the human person and argues against the traditional interpretation of the Prohibitions of 1277 in Oxford as being directed to Thomas Aquinas. The investigation into Kilwardby's theory of knowledge provides new insight on his project to integrate Aristotelian and Augustinian doctrines. The originality of his account of the active nature of perception and his role in shaping standard views on truth, universals and intentions bespeaks of his relevance for understanding later medieval philosophical thought.