The references which were made in Chapter XIV to the work and writings of certain socialists, such as Robert Owen, form another link in this discussion of the development of the co-operation concept. While the experiments in consumers’ co-operation, such as the activities of the Rochdale Pioneers, have had splendid success in many countries, they have demonstrated that they can flourish only in an environment where the co-operative spirit rules. While the experiments in producers’ co-operation have often failed and have not yet as a class been successful, they have testified to the absence of a developed co-operative spirit rather than to the failure of the principle upon which they are based. Peter Kropotkin, whose opposition to socialism was indicated in Chapter XIV, rendered a useful service in writing his _Mutual Aid; a Factor in Evolution_. Kropotkin, a loyal Darwinian, protested against the falsely labeled “social Darwinianism.”[XXI-3] Kropotkin made plain that Darwin’s interpretation of evolution, while stressing the struggle for existence, also pointed out that there is in evolution a powerful tide of co-operation. The logical conclusion of this treatment of evolution, according to Kropotkin, is not a phase of “social Darwinianism” with its emphasis upon a biological struggle in the highest human realms, but a world of human association in which the co-operative spirit has risen to a position of control over physical force and selfish desire. Kropotkin studied animal life extensively and concluded that, although there was among animals a severe struggle against a heartless Nature, there was essentially no bitter struggle for existence “among animals belonging to the same species.”[XXI-3] There is no pitiless inner war for life within this species, and moreover, this alleged war is not a condition of progress. War, declared Kropotkin, is not a condition of social progress. Kropotkin considered the clan and the tribe rather than the individual or even the family the starting point of society. The tribe itself developed a morale on the basis of beliefs in its common origin and in the worship of common ancestors. Then the possession in common of certain lands served to arouse new tribal loyalties. These loyalties expressed themselves in the form of “con-jurations,” sworn agreements, and ultimately in fraternities and guilds for mutual support. Kropotkin believed that primitive man was naturally peaceful, and that he fought from necessity rather than from ferocity. In primitive communal organization the judge and military chief united for “mutual insurance of domination,” drawing to their support the slavish loyalty of the witch-doctor or priest. In the twelfth century, however, the old communal spirit broke forth with “striking spontaneity all over Europe;” it stopped for a time the growth of the despotic monarchies of Europe; it produced endless numbers of communes.