The “dangerous fascination” of Wagner’s “Tristan and Isolde,” most explicitly described by Nietzsche, has affected audiences and private listeners for the last hundred years. Few works of music have exercised so great an influence, not only in the world of music, but on other forms of art and on people’s though and behavior as well. Elliott Zuckerman here discusses the rise and persistence of “Tristanism,” from the time of the inception of the work to the present day.