This volume presents eighty-nine letters exchanged between John Stuart Mill and Auguste Comte between 1841 and 1847. They address important issues of the mid-nineteenth century in philosophy, science, economics, and politics. Cumulatively, these letters provide a humanistic view of Western Europe and its social problems. They add valuable perspective to what we know about the work of Mill and Comte, in a critical period of English and French thought. The correspondence begins with an admiring letter from Mill who considers himself a positivist at the tune and writes to Comte as to an elder...