Plato has reduced the different social functions to four classes, namely: 1, _magistrates_; 2, _warriors_; 3, _farmers_; 4, _artisans_. The two first classes are the governing classes; the two others are the classes governed. The two first apply themselves to moral things: education, science, the defense of the country; the others to material life. This classification of Plato is somewhat too general for our modern societies, which comprise more varied and numerous elements: these divisions, nevertheless, are important, and should be taken account of in morals. Since Plato, there is scarcely any but the socialist Saint-Simon who attempted to classify the social careers. He reduces them to three groups: _industrials_, _artists_, and _scientists_ (savants). The meaning of this classification is this: the object of human labor, according to Saint-Simon, is the cultivation of the globe--that is to say, the greatest possible production; but this is the object of productive labor; it is what is called _industry_. Now, the cultivation of nature requires a knowledge of nature's laws, namely, _science_. Science and invention are, then, the two great branches of social activity. According to Saint-Simon, work--that is to say, industry--must take the place of war; science, that of the laws. Hence no warriors, no magistrates; or, rather, the scientists (savants) should be the true magistrates. Science and industry, however, having only relation to material nature, Saint-Simon thought there was a part to be given to the moral order, to the _beautiful_ or the _good_; hence a third class, which he now calls _artists_, now _moralists_ and _philosophers_, and to whom a sort of religious rôle is assigned. It will be seen that this theory is absolutely artificial and utopian, that it has relation to an imaginary system, and not to the order of things as it is: it is an ingenious conception, but quite impracticable. One of the greatest of modern moralists, the German philosopher Fichte, assigned, in his _Practical Morality_, a part to the doctrine of _professional_ duties; and he began by giving a theory of the professions more complete and satisfactory than any of the preceding ones. Fichte makes of the special professions two great divisions: 1, those which have for their object the keeping up of material life; 2, those which have for their object the keeping up of intellectual and moral life. On the one side, _mechanical labor_; on the other, _intellectual_ and _moral labor_. The object of mechanical labor is _production_, _manufacture_, and _exchange_ of produce; hence three functions: those of =producers=, =manufacturers=, and =merchants=.