Although it is now known--and the researches of modern naturalists bring us every day new proofs--that co-operation has played, and still plays, a most important part in the development of the organic world, nevertheless, the difference between the human struggle for existence and that of the inferior animals is enormous. It is in fact proportionate to the distance separating man from the other animals. And this is none the less true because of that Darwinian theory, which the _bourgeois_ class have ridden to death, little suspecting the extent to which mutual co-operation has assisted in the development of the lower animals. The lower animals fight either individually, or, more often, in little permanent or transitory groups, against all nature, the other individuals of their own species included. Some of the more social animals, such as ants, bees, etc., associate together in the same anthill, or beehive, but are at war with, or indifferent towards, other communities of their own species. Human strife with nature, on the contrary, tends always to broaden association among men, to unite their interests, and to develop each individual's sentiments of affection towards all others, so that united they may conquer and dominate the dangers of external nature by and for humanity. All strife directed towards obtaining advantages independently of other men, and in opposition to them, contradicts the social nature of modern man, and tends to lead it back to a more animal condition. _Solidarity_, that is, harmony of interests and sentiments, the sharing of each in the good of all, and of all in the good of each, is the state in which alone man can be true to his own nature, and attain to the highest development and happiness. It is the aim towards which human development tends. It is the one great principle, capable of reconciling all present antagonisms in society, otherwise irreconcilable. It causes the liberty of each to find not its limits, but its complement, the necessary condition of its continual existence--in the liberty of all. "No man," says Michael Bakunin, "can recognize his own human worth, nor in consequence realize his full development, if he does not recognize the worth of his fellow men, and in co-operation with them, realize his own development through them. No man can emancipate himself, unless at the same time he emancipates those around him. My freedom is the freedom of all; for I am not really free--free not only in thought, but in deed--if my freedom and my right do not find their confirmation and sanction in the liberty and right of all men my equals.