Marcia Colish is one of the most influential scholars of the history of medieval and early modern thought, the author of numerous books and scores of articles in the field, as well as a pioneering President of the Medieval Academy of America. This volume honours her accomplishments with papers by her many colleagues, friends, and former students, who are themselves prominent scholars from across a range of disciplines. The chapters are diverse chronologically and topically, yet they are all stimulated by themes that Prof. Colish has explored during her long and distinguished career. They address the richness of European intellectual history between the twelfth and the sixteenth centuries, treating the multiple heritages of philosophy, theology, political theory, historiography, classical reception, and many other subjects to which her scholarship extends. The volume demonstrates the power of ideas in the development of European history generally, revealing that the careful study of the works of the 'mind' does indeed 'matter'.