This volume addresses the widespread medieval phenomenon of transgression as both a result of and the cause for the exclusion and persecution of those who were considered different. It is widely accepted that the essence of a manuscript cannot be fully grasped without studying its marginalia. Glosses sit on the margins of the text and clarify it, adding a whole new dimension to it and becoming an inextricable part of its content. Similarly, no society can be fully understood without knowledge of what lies on its margins, for the outliers of any given culture provide us with just as much information as its alleged foundational principles. In a time when the Western world ponders building walls up against perceived threats and frightening differences, this multidisciplinary collection of essays based on original and innovative pieces of research shows that it was mostly through tearing down walls that we learned our way forward.