Gordon Rudy 
The Mystical Language of Sensation in the Later Middle Ages [PDF ebook] 

First Published in 2002. This book is about the way medieval authors wrote about union with God and how they used language that refers to the senses to articulate their ideas about how a person can be one with God. Rudy argues that such explicit concepts of the spiritual senses are not sharply distinct from the ideas implicit in broader usage of sensory language in theological writings. These ideas are significant in the history of Christian mysticism, because language that refers to the senses bears directly on several ideas that are central to ideas about union with God.