After this introduction the author enters upon the subject itself. At the beginning of the 19th century the dogma was dominant, that instruction was the panacea for all crimes. Later many of the publicists, including the socialists, advanced the opinion that the true remedy for criminality was education. Just as the first theory was incorrect, Professor Ferri would show that the second is equally so. The question is, can education lead man to good or to evil; and if it can, how far can it lead him? The scientific pedagogues have not treated this question, as far as the author knows. Without furnishing proofs the socialists admit that education can modify man in many respects. Owen, for example, says: “every child may be brought up to have in his later life only good habits, or bad, or a mixture of the two, according to his education.” It is necessary to distinguish three kinds of education—physical, intellectual, and moral. First, a general observation applicable to all kinds of education. In his physical, intellectual, and moral make-up, each individual is the product of a countless number of ancestors, to whom he is bound by unchangeable laws of heredity. From this it is clear that the power of education, which acts only during a limited number of years, is small compared to that of the influences to which a man’s ancestors have been subjected for thousands of years. The question becomes, then: “what are the limits of such modification?” Further it is necessary to determine just how far this modification is due to education, and how far to environment. For education, properly so called, i.e. the direct and methodical influence of the educator upon his pupil, differs in many respects from that of the physical and social environment. This is why the author treats this latter in a special chapter, and limits himself now to education alone. The question is therefore reduced to this: “how far can a man (the educator) modify the constitution of another man (the pupil)?” One more observation should precede the study of the question, namely that a force, or a complexus of forces, can be influenced only by other homogeneous forces. Now when we examine how far physical or biological education can make its influence felt, we see that this influence may be very great, though naturally limited, in proportion to the knowledge we have of the structure and functioning of the organs which it is attempted to modify. As to intellectual education, the results are much less, since the knowledge of the organs involved is much smaller. As to moral education, the following question is one to which pedagogues have given little attention: “how far do morality or immorality, good or bad character, depend upon the education received at home and in school?”