Sociology, by Prof. F.A. Giddings, the first edition of which was
published in 1896 at New York and London, and the leading ideas
of which were sketched by the author in a pamphlet in 1894. I
must leave, however, to literary critics the task of discussing
the points of contact, resemblance, or divergence between these
works and mine.

The different chapters of this book were published first in
the Nineteenth Century ("Mutual Aid among Animals," in September
and November 1890; "Mutual Aid among Savages," in April 1891;
"Mutual Aid among the Barbarians," in January 1892; "Mutual Aid
in the Medieval City," in August and September 1894; and "Mutual
Aid amongst Modern Men," in January and June 1896). In bringing
them out in a book form my first intention was to embody in an
Appendix the mass of materials, as well as the discussion of
several secondary points, which had to be omitted in the review
articles. It appeared, however, that the Appendix would double
the size of the book, and I was compelled to abandon, or, at
least, to postpone its publication. The present Appendix includes
the discussion of only a few points which have been the matter of
scientific controversy during the last few years; and into the
text I have introduced only such matter as could be introduced
without altering the structure of the work.

I am glad of this opportunity for expressing to the editor of
the Nineteenth Century, Mr. James Knowles, my very best thanks,
both for the kind hospitality which he offered to these papers in
his review, as soon as he knew their general idea, and the
permission he kindly gave me to reprint them.