The essays in this Festschrift are celebrations of the human mind in its manifold expressions - philosophical, scientific, historical, aesthetic, political - and in its various modes - analytical, systematic, critical, imaginative, constructive. They are offered to Robert S. Cohen on the occasion of his 70th birthday, in acknowledgment of his own extra- ordinary participation in the life of the mind, and of his unfailing encouragement and facilitation of the participation of others. It is fitting that these volumes should appear in the Boston Studies in the Philosophy of Science, the series which he co-founded so many years ago, and of which he has been the principal editor for more than three decades. (These are perhaps the only volumes of that series which he has not edited or co-edited! ) The three volumes that constitute this Festschrift cover the range of Cohen's interests as a philosopher/scientistlhumanist, as they also represent the spectrum of his professional and personal friendships. (Regretfully, the editors could not include contributions from more of them here. ) The first volume centers around the philosophy and history of the natural sciences and mathematics; Volume Two collects essays related to Marxism and science, philosophy of culture and the social sciences; and the third volume focuses on science and the humanistic understanding in art, epistemology, religion and ethics.