In the Preface to the second edition of my Physiology, published in 1858, it was mentioned that this work was at that time written. The changes that have been since made in it have been chiefly with a view of condensing it. The discussion of several scientific questions, such as that of the origin of species, which have recently attracted public attention so strongly, has, however remained untouched, the principles offered being the same as presented in the former work in 1856. _New York, 1861._ PREFACE TO THE REVISED EDITION. Many reprints of this work having been issued, and translations published in various foreign languages, French, German, Russian, Polish, Servian, &c., I have been induced to revise it carefully, and to make additions wherever they seemed to be desirable. I therefore hope that it will commend itself to the continued approval of the public. _November, 1875._ CONTENTS. CHAPTER I. ON THE GOVERNMENT OF NATURE BY LAW. _The subject of this Work proposed.--Its difficulty._ _Gradual Acquisition of the Idea of Natural Government by Law.--Eventually sustained by Astronomical, Meteorological, and Physiological Discoveries.--Illustrations from Kepler's Laws, the Trade-winds, Migrations of Birds, Balancing of Vegetable and Animal Life, Variation of Species and their Permanence._ _Individual Man is an Emblem of Communities, Nations, and Universal Humanity.--They exhibit Epochs of Life like his, and, like him, are under the Control of Physical Conditions, and therefore of Law._ _Plan of this Work.--The Intellectual History of Greece.--Its Five characteristic Ages.--European Intellectual History._ _Grandeur of the Doctrine that the World is governed by Law._ Page 1 CHAPTER II. OF EUROPE: ITS TOPOGRAPHY AND ETHNOLOGY. ITS PRIMITIVE MODES OF THOUGHT, AND THEIR PROGRESSIVE VARIATIONS, MANIFESTED IN THE GREEK AGE OF CREDULITY. _Description of Europe: its Topography, Meteorology, and secular Geological Movements.--Their Effect on its Inhabitants._ _Its Ethnology determined through its Vocabularies._ _Comparative Theology of Greece; the Stage of Sorcery, the Anthropocentric Stage.--Becomes connected with false Geography and Astronomy.--Heaven, the Earth, the Under World.--Origin, continuous Variation and Progress of Greek Theology.--It introduces Ionic Philosophy._ _Decline of Greek Theology, occasioned by the Advance of Geography and Philosophical Criticism.--Secession of Poets, Philosophers, Historians.--Abortive public Attempts to sustain it.--Duration of its Decline.--Its Fall._ 23 CHAPTER III. DIGRESSION ON HINDU THEOLOGY AND EGYPTIAN CIVILIZATION. _Comparative Theology of India; its Phase of Sorcery; its Anthropocentric Phase._