While historians of the book and of reading in the Middle Ages have pored over the evidence offered up by Christian Latinity – and, betting on cultural continuity, have not been afraid to reach back to Antiquity and forward to the Renaissance to clarify or contextualise their own readings – they have been chary of the abundant materials to be found in Byzantium. Greek, in its Christian idiom, is ‘not read’ in the pages of specialist studies like Mary Carruthers's The Book of Memory and popular surveys such as Alberto Manguel's A History of Reading. This ‘not read’ is not easy to justify: the earliest writings of Byzantium represent the shared patristic and monastic heritage of East and West, while in later texts the ‘readerly’ gestures and habits of earlier eras are replayed and rearticulated. Here, the celebrated conservatism of the Byzantines might be an advantage. In fact, the history of the book in the Christian East (when this history is ‘read’) challenges certain comfortable and well-established disciplinary formulations, necessitating their revision or even rejection. For the purposes of this essay, Byzantium's role will not be to supplement the (technological) history of the book that has emerged in the West; rather, by restoring a group of metaphors usually considered technological to their ethical ground, an ‘Eastern approach’ will displace them from the field of inquiry of the history of material texts and of mnemotechnique. Their estrangement will, nonetheless, enrich the history of reading, and along the way, as we will see, Byzantium will provide a new perspective on a locus classicus of this discipline in the West: Augustine's famous encounter with the silence of his teacher Ambrose, in the face of his book.

As my title suggests, I wish to interrogate the heart as master trope for the book in the European Middle Ages. Tracing a genealogy forward from Paul's metaphor of the ‘fleshy tablets of the heart’ in 2 Corinthians 3: 3, Western historians of the book – most notably Eric Jager – have glossed the heart as a surface for writing, a figure for the memory, and ultimately a model of the self. To be sure, the heart functions as a materially book-like metaphor in East and West; doubtless, it acts as a figure for memory across the whole Christian oikoumene.