The relations between crimes against the person and the price of alcohol, and between crimes against property and the price of wheat, also belong to this department of the study of crime. Society prepares crimes, as Quetelet said; the criminal is the instrument that executes them. “The social environment,” Lacassagne has well said, “is the cultivation medium of criminality; the criminal is the microbe, an element which only becomes important when it finds the medium which causes it to ferment: every society has the criminals that it deserves.”

It is impossible to over-estimate the importance of the social factor in crime. To some extent it even embraces the others, and can be made to regulate and neutralise them. But we cannot deal wisely with the social factor of crime, nor estimate the vast importance of social influences in the production or prevention of crime, unless we know something of the biology of crime, of the criminal’s anatomical, physiological, and psychological nature. This book is concerned with the study of the criminal man.

CHAPTER II.

THE STUDY OF THE CRIMINAL.

When Homer described Thersites as ugly and deformed, with harsh or scanty hair, and a pointed head, like a pot that had collapsed to a peak in the baking—