The heavenly bodies, the earth that we inhabit, the elements that it contains, as well as the animals and plants that live on its surface, - in fact, all the things that constitute the material universe and all the phenomena that take place therein,-are the subjects of a distinct group of sciences known as the physical and the natural sciences. But in this vast world there are other subjects no less worthy of study, namely, men themselves, living in society; in fact, they could not possibly live otherwise. The relations that unite men socially form the subject of a separate group of sciences, called the social sciences. As there are among men many kinds of social relations, - moral, legal, economic, political, religious, and, finally, linguistic relations which serve as a vehicle for all the others, - so there are many distinct social sciences, known as ethics, law, political economy, politics, the science of religions, and the science of languages.1 It is true that the lines of...