This story is derived from as human a document as ever existed; and, because of its uncommon nature, perhaps no one thing contributes so much to its value as its authenticity. It is an autobiography, and more: in part it is a biography; for, in telling the story of my life, I must relate the history of another self-a self which was dominant from my twenty-fourth to my twenty-sixth year. During that period I was unlike what I had been, or what I have been since.