While in Brussels, Marx received an invitation from the London Central Committee of the Communist League to join that society. This league had been founded in Paris in 1836, for the purpose of propagating communist opinions among the working men of Germany. Its organization was analogous to that of the International and other societies of the same kind. A certain number of members constituted a _Gemeinde_, the several _Gemeinden_ in the same town constituted a _Kreis_, a number of _Kreise_ were grouped into a leading _Kreis_, and at the head of the whole was the Central Committee, which was chosen at a general congress of deputies from all the _Kreise_, and which had since 1840 had its seat in London. The method of the league was to establish, as a sphere of operation, German working men's improvement associations everywhere. The travelling custom of German working men greatly facilitated this work, and numbers of these associations were soon founded in Switzerland, England, Belgium, and the United States. The reason its committee applied to Marx was that he had just published a series of pamphlets in Brussels, in which, as he tells us, he "submitted to a merciless criticism the medley of French-English socialism and communism and of German philosophy, which then constituted the secret doctrine of the League," and insisted that "their work could have no tenable theoretical basis except that of a scientific insight into the economic structure of society, and that this ought to be put into a popular form, not with the view of carrying out any utopian system, but of promoting among the working classes and other classes a self-conscious participation in the process of historical transformation of society that was taking place under their eyes." This is always with Marx the distinctive and ruling feature of his system. The French schemes were impracticable utopias, because they ignored the laws of history and the real structure of economic society; and he claims that his own proposals are not only practicable but inevitable, because they strictly observe the line of the actual industrial evolution, and are thus, at worst, plans for accelerating the day after to-morrow. But, besides this difference of principle, Marx thought the League should also change its method and tactics. Its work, being that of social revolution, was different from the work of the old political conspirators and secret societies, and therefore needed different weapons; the times, too, were changed, and offered new instruments. Street insurrections, surprises, intrigues, _pronunciamentos_ might overturn a dynasty, or oust a government, or bring them to reason, but were of no avail in the world for introducing collective property or abolishing wage labour. People would just begin again the day after to work for hire and rent their farms as they did before. A social revolution needed other and larger preparation; it