A critical portrait traces the subject's family background and early influences, recounts his development of criminal anthropology and major theories, and surveys contemporary opposition, debates over female and political criminality, criminal psychology, and his reform efforts in jurisprudence and agrarian questions. The book evaluates his methods, personality, and claims about genius, considers the wider significance of criminal anthropology, and documents his unconventional investigations into spiritualism. Chapters summarize predecessors, outline social and legal implications, and conclude with bibliographic appendices and a tabular account of positivist thought.