If man, from the physical point of view, is first of all a product of nature, he is, from the point of view of intelligence, above all a product of society. The most important organs of the nervous system form, develop, differentiate, and integrate under the influence of the social milieu, just as the purely physical part of man is formed and developed under the influence of the physical milieu by the natural differentiation and integration of forces. The economic activity of society, work, customs, habits, laws, political liberty, authority, religion, science, art, in short, all of social life, forms and educates man, gives to his efforts, to his intellectual, moral and aesthetic needs, this or that direction, pushing in this or that sense the complete development of the superior organs of the nervous system (Lilienfeld 1873; cited in Schmoller 1902: 169, note 81).