Consequently I thought that a book, written on Mutual Aid as a Law of Nature and a factor of evolution, might fill an important gap. When Huxley issued, in 1888, his "Struggle-for-life" manifesto (Struggle for Existence and its Bearing upon Man), which to my appreciation was a very incorrect representation of the facts of Nature, as one sees them in the bush and in the forest, I communicated with the editor of the Nineteenth Century, asking him whether he would give the hospitality of his review to an elaborate reply to the views of one of the most prominent Darwinists; and Mr. James Knowles received the proposal with fullest sympathy. I also spoke of it to W. Bates. "Yes, certainly; that is true Darwinism," was his reply. "It is horrible what 'they' have made of Darwin. Write these articles, and when they are printed, I will write to you a letter which you may publish." Unfortunately, it took me nearly seven years to write these articles, and when the last was published, Bates was no longer living. After having discussed the importance of mutual aid in various classes of animals, I was evidently bound to discuss the importance of the same factor in the evolution of Man. This was the more necessary as there are a number of evolutionists who may not refuse to admit the importance of mutual aid among animals, but who, like Herbert Spencer, will refuse to admit it for Man. For primitive Man--they maintain--war of each against all was the law of life. In how far this assertion, which has been too willingly repeated, without sufficient criticism, since the times of Hobbes, is supported by what we know about the early phases of human development, is discussed in the chapters given to the Savages and the Barbarians. The number and importance of mutual-aid institutions which were developed by the creative genius of the savage and half-savage masses, during the earliest clan-period of mankind and still more during the next village-community period, and the immense influence which these early institutions have exercised upon the subsequent development of mankind, down to the present times, induced me to extend my researches to the later, historical periods as well; especially, to study that most interesting period--the free medieval city republics, of which the universality and influence upon our modern civilization have not yet been duly appreciated. And finally, I have tried to indicate in brief the immense importance which the mutual-support instincts, inherited by mankind from its extremely long evolution, play even now in our modern society, which is supposed to rest upon the principle: "every one for himself, and the State for all," but which it never has succeeded, nor will succeed in realizing.