But for these the social theorist cares nothing. Only that is of importance to him which rests upon an essential difference. And of these also there are enough, because the causes of them are numerous. What is here decisive is the variation in the view of world and life, is the difference of national character, is the varying degree of vision into the essence of social development or of understanding concerning accepted principles, is the varying measure of ripeness and education of the masses, is the difference in economic development in the various lands, etc. But I cannot possibly exhaust the points of contradiction and strife which arise out of these manifold and effective causes. I shall here simply present certain matters which seem to me especially important because essentially significant. My duty as to this problem can be, again, only that of a theorist who tries to make a clear explanation, who desires not to work upon your will but upon your intelligence, who does not carry in his hand the brand of agitation but the lamp of illumination. If I do not pay attention to some points of difference which may seem to you of supreme importance, it is not because I do not myself recognise this importance, but because I suppose the contradiction that comes to expression in them to be either out of date or only imaginary, or because I go back of them to the deeper, essential differences. Thus, for example, the alternative, _trade unions_ or _a working-men's party_, is either the expression of a deeper opposition concerning which I shall later speak, or it is a question that does not concern us in these days. Thus concerning all those representatives of the working-men's movement who place themselves upon the platform of legal struggle. These men know that politics and trade unions are like the right and left legs upon which the proletariat marches; that political part-taking is needed in order to obtain influence upon legislation; that economic organisation is needed in order to discipline and educate the masses. The only question can be now as to the degree, the more or less, of the one or the other form of social agitation;--always within the limits of legal agitation on the part of the working men. Any such question cannot be general; it must be decided separately in each place and case. The economic ripeness of the masses, the degree of political freedom, and much else, must decide.