This work is Engels' testimony with regard to the method employed by them in arriving at their philosophical conclusions. It is the statement of the philosophical foundations of modern socialism by one who helped to lay them; it is an old man's account of the case upon the preparation of which he has spent his entire life, for, this work, short as it is, represents the results of forty years of toil and persevering effort. As the "Communist Manifesto" was a gage flung with all the impetuosity of youthful impatience into the face of constituted authority, so this is the deliberate statement of the veteran, who has learned the game too well to leave any openings, and proceeds to the demolition of pet opinions in a quiet, deadly and deliberate fashion. Step by step, the argument is built up. The ghosts of old controversies long since buried are raised, to show how the doctrine imperishably associated with the names of Marx and Engels came into existence; the "Young Hegelians," the "Tuebingen School," and finally Feuerbach himself are summoned from the grave to which the Revolution of 1848 had consigned them. Still, ancient history as these controversies are from the German standpoint, such is the backwardness of philosophy among English-speaking peoples, that we find Engels exposing again and again fallacies which persist even in our time, and ridiculing sentiments which we receive with approbation in our political assemblies, and with mute approval in our churches and conventicles. The anti-religious note is noticeable throughout, in itself an echo of controversies long past, when the arguments of the critics of the Bible were creating now fury, now dismay, throughout Christendom, before the Higher Criticism had become respected, and before soi-disant sceptics could continue to go solemnly to church. Moreover, the work was written in German for German workmen for whom religion has not the same significance as it apparently still continues to possess for the English-speaking people, whose sensitiveness upon the subject appears to have outlived their faith. However that may be, religious bodies possess a curious and perhaps satisfactory faculty of absorbing the truths of science, and still continuing to exist, and even to thrive, upon what the inexperienced might easily mistake for a deadly diet. Under the circumstances there is no reason why Engels' remarks should affect even the timorous, although it must be remembered that a very able English socialist philosopher is reputed to have damaged his chances irretrievably by an ill-judged quotation from Mr. Swinburne.