This anthology represents the first large-scale attempt to present–and draw some morals and predictions from–the complex history of the concept of matter from Thales and Plato down to Marx and Heisenberg. The Concept of Matter is a collection of twenty-seven papers, each by a philosopher or scientist whose particular contribution to the dialogue on the concept is well known and here summarized and extended. From the symposium held in the fall of 1961 at the University of Notre Dame, Father McMullin has included not only the revised versions of those twenty-seven papers, but also an edited selection of comments and interchanges at the symposium itself–the dialogues of a distinguished gathering, some of the world’s greatest scholars. The discussions bridge the concept of matter from the Greek and medieval interpretations through the transformation of the concept of matter into the redefinition of the concept of mass, to finally the dematerialization of matter by modern science. A study of the evolution of this crucial concept illuminates the interrelation between the philosophical and the scientific approaches to Nature which can be more thoroughly grasped in terms of the development and constantly changing views towards related concepts like matter and mass. Contributors: C. Lejewski, L. Esliek, J. Fitzgerland, J. Owens, N. Luyten, E. McMullin, A. Wolter, M. Fisk, M. B. Hall, C. Taliaferro, M. B. Hesse, C. Mast, J. Smith, A.R. Caponigri, N. Lobkowiez, K. Sayre, R. Rorty, R. Johann, N.R. Hnason, A.E. Woodruff, C. Misner.