A student of Etienne Gilson and Joseph Owens, John P. Doyle taught medieval and Scholastic philosophy at Saint Louis University for forty years. Of continuing interest to Doyle has been the thought of Francisco Suarez, S.J. On this topic Doyle has published over a dozen articles and four English translations of portions of Suarez's key works such as the Disputationes metaphysicae and Index locupletissimus. In turn, through Suarez, Doyle was led to the thought of a vast array of late Scholastic figures, the interest in which would sustain his intellectual fervour for the rest of his career and result in many more scholarly studies and additional volumes of English translations. A theme uniting Doyle's research in these areas is "nothing." That is, for Suarez, non-beings or beings of reason (entia rationes), distinguished from real being (ens reale), spanned the range of the thinkable to the contradictory or impossible objects, such as the square-circle, goat-stag, and, of course, the hircocervus. Accordingly, Suarez did not consider beings of reason as falling under the scope of metaphysics.Nevertheless, as though yielding to some secret temptation, the Jesuit Scholastic devoted the final disputation of his Disputationes metaphysicae to a consideration of such a "shadowy reality." Where Suarez would not dare to tread other seventeenth-century thinkers would march on; Doyle chronicled and clarified their many adventures and explorations of non-being and even supertranscendental nothingness, the contrapuntal tone to supertranscendental being.This volume celebrates the life and career of one of those rare kinds of scholars who has mastered an entire field of inquiry and thought; it is offered in honour of John P. Doyle by his colleagues, students, and friends.