EVOLUTION
ITS NATURE, ITS EVIDENCES, AND ITS
RELATION TO RELIGIOUS THOUGHT

BY
JOSEPH LE CONTE

AUTHOR OF “RELIGION AND SCIENCE,” ETC.
AND PROFESSOR OF GEOLOGY AND NATURAL HISTORY IN THE
UNIVERSITY OF CALIFORNIA

SECOND EDITION, REVISED

NEW YORK:
D. APPLETON AND COMPANY,
72 FIFTH AVENUE.
1897.

PREFACE TO THE SECOND EDITION.

The three years which have elapsed since the publication of the first edition of this work have been years of great activity of thought on many of the subjects treated therein. Some changes and additions seemed therefore imperatively called for.

For example: There has sprung up recently among the foremost writers on evolution a warm discussion on the factors of evolution, their number and relative importance. I have therefore added a chapter ([Chap. III, Part II]) on this subject—not, indeed, to discuss it fully (for this would be impossible in the limits of a chapter), but to put the mind of the reader in position to understand it and to judge for himself.

Again: Every reader of the first edition must have remarked that there are many fundamental religious questions which I have not touched at all in [Part III]. I had avoided these because my own mind was not yet fully clear. I regarded what I then wrote as only a little leaven in a very large lump. I was willing to wait and let it work. In the mean time it has worked in my own mind, and I hope in the minds of others. I have therefore added two chapters to this part. In one I simply carry out to their logical consequences the doctrine of the Divine Immanency. This brings up the questions of First and Second Causes; of General and Special Providence; of the Natural and the Supernatural; of Mind vs. Mechanics in Nature, etc., and shows the necessary changes of view which are enforced by the theory of evolution.

In the other I take up very briefly “The Relation of Evolution to the Doctrine of the Christ.” In the discussion of this I restrain myself strictly within the limits of the subject as stated above.

The only other important changes are in [Chapter IV, Part III], “On the Relation of Man to Nature.” As I regard this as the most important chapter in the whole book, I have endeavored still further to enforce my view of the origin of man’s spirit, and especially to make it clearer by means of several additional illustrations.

Joseph Le Conte.

Berkeley, Cal., July 1, 1891.

PREFACE TO THE FIRST EDITION.

The subject of the following work may be expressed in three questions: What is evolution? Is it true? What then? Surely, there are no questions of the day more burning than these. Much has been written on each of them, addressed to different classes of minds: some to the scientific, some to the popular, and some to the religious and theological; but nothing has yet appeared which covers the whole ground and connects the different parts together. Much, very much has been written, especially on the nature and the evidences of evolution, but the literature is so voluminous, much of it so fragmentary, and most of it so technical, that even very intelligent persons have still very vague ideas on the subject. I have attempted to give (1) a very concise account of what we mean by evolution, (2) an outline of the evidences of its truth drawn from many different sources, and (3) its relation to fundamental religious beliefs. I have determined, above all, to make a book so small that it may be read through without much expense of time and patience. But the subject is so large that in order to do so it was necessary to sacrifice all but what was most essential, and to forego all redundancy (the bane of so-called popular science) even at the risk of baldness and obscurity. Nevertheless, I hope that the first and second parts will be found not only interesting to the intelligent general reader, but even profitable to the special biologist. I have tried to make these parts as untechnical as possible, but I hope not on that account the less scientific. For I am among these who think that it is not necessary to be superficial in order to be popular—that science may be adapted to the intelligent popular mind without ceasing to be science.

The third part seems to me still more important just now. There is a deep and widespread belief in the popular mind, and even to some extent in the scientific mind, that there is something exceptional in the doctrine of evolution as regards its relation to religious thought and moral conduct. Other scientific theories have required only some modifications of religious conceptions, but this utterly destroys the possibility of all religious belief by demonstrating a pure materialism. Now this, I believe, is a complete misconception. Thinking men are fast coming to see this; some, indeed, have mistaken the change for a reaction against evolution. It is a reaction not against evolution, but only against its materialistic implication. Evolution is more and more firmly established every year. The tide of conviction is one which knows no ebb. Some clear statement, in brief space, of its true relation to religious thought seems, therefore, very important at this time.

Berkeley, Cal., May, 1887.

CONTENTS.

[PART I.]
WHAT IS EVOLUTION?
[CHAPTER I.]
ITS SCOPE AND DEFINITION.
	PAGE
A type of evolution—Development of an egg	[3]
Universality of evolution—Pervades all nature and concerns all departments of thought—One half of all science—Illustrated (1) by human body, (2) by solar system, (3) by society, (4) by earth, (5) by organic kingdom—The term evolution usually, but not rightly, confined to this last	[3]
Definition of evolution—I. Progressive change—Shown in the animal body, or the Ontogenic series—In the animal scale, or the Taxonomic series—In the geological, or Phylogenic series—The three series similar, though not identical	[8]
II. Change according to certain laws—Three laws of succession of organic forms	[11]
(a) Law of differentiation—Early forms are generalized; afterwards separated into specialized forms—Illustrated by fishes, by birds—Whole process of differentiation illustrated by growth and branching of a tree	[11]
(b) Law of progress of the whole—Mistake of confounding evolution with upward progress—How far true, and how far false—Illustrated by branching tree—Examples of this mistake in the popular mind—In the scientific mind	[13]
(c) Law of cyclical movement—Shown in geological history—Age of mollusks, fishes, reptiles, mammals, man—Illustrated again by a branching tree—Increasing complexity as well as height—Illustrated by diagram	[16]
The above three laws are laws of evolution—Differentiation—Shown in the development of an egg, the type of evolution	[19]
Progress of the whole—Not progress of all parts—Shown in the development of an egg	[22]
Cyclical movement—Less fundamental than other two—Shown in Ontogeny of body, of mind—Increasing complexity—Necessity of continued advance—Otherwise deterioration—All these laws shown in progress of society—-Differentiation shown—Progress of the whole but not of all parts shown—Cyclical movement shown—In social evolution, however, there is another element, viz., conscious voluntary progress—-This kind of evolution contrasted with the other	[22]
III. Change by means of resident forces—This is the point of dispute—Sense in which we use term resident forces—Does not touch question of origin of natural forces	[27]
The two views of the origin of organic forms briefly contrasted—As to whether natural or supernatural—As to variability, definite or indefinite—As to change from one species to another by transmutation or substitution—As to universality of law of continuity	[29]
[CHAPTER II.]
THE RELATION OF LOUIS AGASSIZ TO THE THEORY OF EVOLUTION.
General misunderstanding on this subject—Necessary to give sketch of history of the idea—Greeks, Lucretius, Swedenborg, and Kant—First scientific presentation by Lamarck—General character of Lamarck’s views—Failed, and rightly so—Next, Chambers’s “Vestiges of Creation”—Its general character—Failed, and rightly so—Some think this unfortunate—Why not so—An obstacle must be removed and a basis laid	[32]
The obstacle removed—Old views in regard to forces—Correlation of forces established—But vital force considered exception—Therefore living forms also supposed exception to mode of origin of other forms—Then vital forces also correlated—Therefore, a priori probable that living forms also correlated with other forms as to mode of origin—Thus obstacle removed	[35]
The basis laid—Agassiz laid inductive basis of evolution, although he refused to build—He established the laws of evolution and perfected the method of comparison—Importance of method discussed—The method of notation—The method of experiment—The difficulty of applying these to life phenomena—Method of comparison shown—(1) In Taxonomic series—(2) In Ontogenic series—(3) In Phylogenic series—Cuvier the great worker by comparison in the Taxonomic series—Agassiz in the Ontogenic and Phylogenic—Agassiz also established the three laws of evolution given in previous chapter—Thus he laid foundation—Why he did not build—Supposed identity of evolution and materialism—The obstacle being removed and the basis laid, when evolution again brought forward it was universally accepted, because the world was prepared—Place of Agassiz and Darwin compared—Formal science vs. physical science—Illustrated by relation of Kepler to Newton—Relation of Agassiz to time cosmos similar to that of Kepler to space cosmos—So Darwin to Newton—Some reflections on the above—Gravitation is the law of space cosmos—Evolution of time cosmos—Of the divine spheral music gravitation is the chordal harmony and evolution the melody	[37]
[PART II.]
EVIDENCES OF THE TRUTH OF EVOLUTION.
[CHAPTER I.]
GENERAL EVIDENCES OF EVOLUTION AS A UNIVERSAL LAW.
Evolution is continuity, causal relation, gradual becoming—Increasing acceptance of this idea—First accepted for inorganic forms, mountains, continents and seas, rocks and soils, earth as a whole, heavenly bodies—Therefore acknowledged for all inorganics—Influence of geology in bringing about this change—Organic forms: acknowledged for individuals, true for classes, orders, families, genera—Races and varieties also formed gradually—Artificial species formed gradually—Examples of gradual changes in wild species—Hyatt’s researches—Other examples—Summing up of general evidence—Sufficient ground for induction—But evolution is not only inductively probable but certain, axiomatic—It is the law of causation applied to forms, and therefore a necessary truth	[53]
[CHAPTER II.]
SPECIAL PROOFS OF EVOLUTION.
Introductory.
Special proofs necessary—Evolution, though certain, is not yet accepted by the popular mind—Different departments from which proofs are drawn	[67]
Origin of new organic forms; the old view briefly stated—Necessary to give a brief statement of theories—Old view—Permanency of specific types—Supernatural origin of species—Centers of creation—Explanation of facts of geographical distribution—Of geological distribution—Modification of extreme view—Variability, but within limits—Illustrated	[68]
The new view briefly stated—Indefinite variability of organic forms—Effect of environment on rigid forms—On plastic forms—Taxonomic groups represent degrees of kinship	[72]
Factors of evolution—(1) Physical environment—(2) Use and disuse of organs—(3) Natural selection—(4) Sexual selection—(5) Physiological selection—Its necessity shown—Its operation explained—Compared with natural selection—Cause of variation unknown—Explanation of this is the next great step in the theory of evolution	[73]
[CHAPTER III.]
THE GRADES OF THE FACTORS OF EVOLUTION AND THE ORDER OF THEIR APPEARANCE.
Factors of evolution restated; their grades and the order of their introduction shown—Lamarckian factors, first in order because they precede sexual reproduction—(1) Environment—(2) Use and disuse—With sexual reproduction selective factors introduced—(3) Natural selection—(4) Physiological selection—(5) Sexual selection—With man was introduced (6) the rational factor—In this process two striking stages—viz., the introduction of sex and the introduction of reason—Effect of each to hasten the steps of evolution—The last by far the greater change	[81]
Contrast between organic and human evolution—(1) The meaning of term fittest in each—(2) Destiny of the weak and helpless in each—(3) The nature of evolutionary transformation in each—(4) The law of strait and narrow way applied in each—(5) Human evolution is a different kind and on a higher plane	[88]
Application to some questions of the day.
I. Neo-Darwinists, their position explained—Reasons for dissenting—(a) Lamarckian factors preceded all others—(b) Though now subordinate, they still underlie and condition all other factors—(c) Shown by comparison of phylogeny with ontogeny	[92]
II. Human progress not identical with organic evolution—Mistake of the materialists—But neither is it wholly different, as some suppose	[96]
III. Neo-Darwinism is fatal to hopes of human progress—Reason may use freely Lamarckian factors, but can not use natural selection in the same way as Nature does	[97]
[CHAPTER IV.]
SPECIAL PROOFS FROM THE GENERAL LAWS OF ANIMAL STRUCTURE, OR COMPARISON IN THE TAXONOMIC SERIES.
General Principles.
Analogy and homology—Defined and illustrated by examples—Wings and limbs—Lungs, gradual formation of, traced in the Taxonomic series—Traced in the Ontogenic series—Examples of homology in plants: tuber, cactus-leaf, acacia-leaf—Definitions repeated and further explained—Common origin is the only explanation of homology	[99]
Primary divisions of the animal kingdom—True ground of such divisions is ability to trace homology—We take examples only from vertebrata and articulata—Compare to styles of architecture—To machines—To branching stem	[107]
[CHAPTER V.]
PROOFS FROM HOMOLOGIES OF THE VERTEBRATE SKELETON.
Common general plan—In several respects—Strongly suggestive of common origin—Details of structure demonstrative of the same	[111]
Special homology of vertebrate limbs	[113]
Fore-limbs—Comparison of fore-limbs of mammals, birds, reptiles, and fishes, part for part—Gradual changes in collar-bone and coracoid—In position of elbow—In bones of forearm—In position of wrist—In the tread—The term manus—Number of toes—Modifications for flight in various animals—For swimming in whales and fishes	[113]
Hind-limbs—Comparison of hind-limbs of several mammals—Position of knee—Of heel—Plantigrade and digitigrade—Degrees of the latter—Number of toes—General law in regard to number of similar parts—Order of toe-dropping in artiodactyles—In perissodactyles	[121]
Genesis of the horse—Changes in foot-structure—Same true of other parts of skeleton—Only natural explanation is derivation—Nature compared with man in mode of working—Angels—Griffins—Centaurs—Muscular and nervous systems—Visceral organs	[126]
[CHAPTER VI.]
HOMOLOGIES OF THE ARTICULATE SKELETON.
Illustrations from this type—Plan of structure entirely different—General plan of structure explained and modifications shown—Shrimp—Modification of segments and of appendages for various purposes: swimming, walking, eating, sense—Illustrated by other crustaceans—By myriapods—By marine worms—Crabs—Embryonic development of crabs—insects—Modification of segments and appendages—Mouth parts of insects	[132]
Illustration of the law of differentiation—Cells—Segments—Individuals—Homologies in other departments of animals, but these are less familiar—Between primary groups, homology untraceable in adult forms—But these also probably connected by common origin—Different views as to origin of vertebrates	[144]
[CHAPTER VII.]
PROOFS FROM EMBRYOLOGY, OR COMPARISON IN THE ONTOGENIC SERIES.
Resemblance of the three series—Frog, in Ontogeny passes through main stages of Taxonomy and Phylogeny—Resemblance only general—Many steps dropped out in Ontogeny	[148]
(1) Ontogeny of tailless amphibians—The frog: fish stage, perennibranch stage, caducibranch stage, aneural stage—Same stages in Phylogeny	[150]
(2) Aortic arches—Those of lizard described—Origin from gill-arches of fish—Change from one to the other in Ontogeny of a frog—Same changes in Phylogeny of lizard—Embryonic condition of mammalian heart and vessels—Gradual change and final condition in birds—In mammals—Gradual decrease in number of aortic arches as we go up the vertebrate scale—Cogency of the argument from aortic arches	[151]
(3) Vertebrate brain—Fish brain—Brain of reptiles, birds, mammals, man compared—Human brain passes through similar stages—Changes in complexity of structure in Taxonomy—Same changes in Ontogeny of mammals—Same in Phylogeny of reptiles, birds, mammals	[162]
Cephalization—Explanation of, in body, in mind	[171]
(4) Fish-tails—Homocercal and heterocercal—Vertebrated and non-vertebrated—Order of change in Ontogeny—Same in Phylogeny—Similar changes in birds’ tails in Ontogeny and Phylogeny—In other tailless animals—Examples from articulates, insects, crustaceans, etc.	[172]
Illustration of the differentiation of the whole animal kingdom—Development of eggs of all kinds of animals—This a type of changes in Phylogeny—Why Ontogeny repeats Phylogeny—Law of acceleration	[176]
Proofs from rudimentary and useless organs—Examples from whale: Teeth—Limbs—Hair—Olfactive organs—Examples from man: muscles, cæcal appendage—Significance of useless organs	[179]
[CHAPTER VIII.]
PROOFS FROM GEOGRAPHICAL DISTRIBUTION OF ORGANISMS.
Geographical faunas and floras—Conditions which limit	[183]
Temperature-regions—Illustrated by plants—In latitude and in elevation—Same in animal species	[184]
More perfect definition of regions—Range of different Taxonomic groups—Gradual shadings on borders of range—Shadings out of individuals in number and vigor, but not in specific character—As if centers of origin—Effect of east and west barriers—Temperature regions repeated south of the equator, but not species—As if centers of origin	[186]
Continental faunas and floras—Temperature zones continuous, but not species—Reason: ocean barriers—As if centers of origin—Polar regions: one. Why—Temperate zone—Different species in different continents—Species of United States and of Europe almost wholly different—As if origin local—Exceptions—(1) Introduced species—(2) Hardy or else wide-migrating species—(3) Alpine species—Tropical zone of two continents still more different—Same true of south temperate zone	[188]
Subdivisions of continental faunas and floras—Illustrated by fauna and flora of United States	[191]
Special Cases—Australia—Madagascar—Galapagos—River mussels	[192]
Marine species—Same principles applicable—Therefore organic forms grouped in regions, sub-regions, provinces, etc.—Primary regions according to Wallace—According to Allen	[192]
Theory of the origin of geographical diversity—Specific centers of creation—Objections to. The element of time left out—Progressive change in unlimited time, or evolution the only rational explanation—This connects with geographical changes in geological times, especially the Glacial epoch—Geographical diversity in other times	[193]
Most probable view of the general process—Last great period of change was the Glacial epoch—This, therefore, is the key to geographical distribution—Condition of things during the Glacial epoch—-In America—Changes in temperature—In physical geography and in species—In Europe—Application of principles	[196]
(1) Australia—Characteristics of its fauna—Explanation of—Isolation very early—Position of marsupials and monotremes in the Taxonomic scale—Australia isolated before the Tertiary—Effect of competition on evolution	[200]
(2) Africa—African region defined—Two groups of its mammals, indigenes, and invaders—Effect of the invasion	[204]
(3) Madagascar—Characteristics of its fauna—Relation to African indigenes—Separated before the invasion—Significance of its lemurs	[205]
(4) Island life—Two kinds of islands—Defined and illustrated by examples—(a) Continental islands—General character of fauna—Illustrated by Madagascar, New Zealand, British Islands, coast-islands of California—Characteristics of the faunas of these explained—(b) Oceanic Islands—Defined—Characteristics of faunas and their origin	[207]
(5) Alpine species—Characteristics of and their origin explained—Migrations of Arctic species during Glacial times, and their isolation on mountains	[215]
Objection—Mode of change of species on borders of ranges—Examples—Sweet-gum—Sequoia	[217]
Answer—Distribution of these forms in time, and their migrations—They are remnants—Intermediate forms are extinct	[219]
[CHAPTER IX.]
PROOFS FROM VARIATION OF ORGANIC FORMS, ARTIFICIAL AND NATURAL.
Limitation of the use of experiment in morphology—Unconscious experiments in breeding, and their results—Principles involved—Inheritance, immediate and ancestral—Effect of true breeding long continued—Method of selection illustrated by diagram—Formation of a race—Process the same in nature—Show selective effect of physical environment—Of organic environment—Of migrations—Of unlimited time—Other factors of change, and their effects shown in nature and in domestication—Differences between artificial and natural species	[222]
First difference, reversion—The tendency to reversion described—The reason explained—Illustrated by the case of the pointer	[229]
Second difference, intermediate forms—Reason is, these are eliminated in nature	[232]
Third difference, cross-fertility—Natural species are usually cross-sterile—Degrees of cross-sterility—Two bases of species, morphological and physiological—Two kinds of isolation, sexual repugnance and cross-sterility—Latter most essential—Illustrated by plants and hermaphrodite animals—Former only higher animals—Natural laws interfered with by domestication—Illustrated by plants and animals	[232]
Law of cross-breeding—Effect of close breeding—Of crossing varieties to a limit—The law investigated—Reproduction in lowest organisms—Fission—Gemmation—Internal gemmation—Sex introduced—Effect of, is funding of differences in offspring and tendency to variation—Sexual and non-sexual reproduction compared—Separation of sex elements—Of sex-individuals—Introduction of sex-attraction—Funding of greater differences in offspring—Crossing of varieties—Diagram illustrating effect in vigor—Effect also in plasticity—Application of these principles—Necessity of sexual isolation to produce species—Origin of cross-sterility and thus of species by Dr. Romanes’s idea—Why artificial varieties are cross-fertile—Geographical species sometimes cross-fertile—Application of principles—Absence of intermediate links in natural species explained—Under what conditions such are found—Further explanation of this point—Illustrated by a growing tree	[236]
Objection answered—Intermediate links ought to be found fossil—Answer (1) Imperfection of record. (2) The term species indefinite. (3) Transitions between all other taxonomic groups abundant. (4) Between species, also, both living and fossil—Of fossil, Planorbis of Steinheim—Other examples—(5) Why transition-forms are rare—Answer—Changes in every department of nature are paroxysmal—Illustrated—So the steps of evolution paroxysmal—Critical periods in evolution—Causes of rapid advance—Apparent discontinuity between species—(1) changes paroxysmal—(2) Brooks’s idea—Male sex is the progressive element—Illustrated by society—Effect of prosperous times—Mrs. Treat’s experiments—Hard times produce excess of males, and therefore tend to diversity—Summary	[248]
Objection—Egyptian drawings and mummy plants, show no change—Answer (1) Time too short. (2) We are now in time of slow change. (3) All species don’t change, most become extinct. (4) Evolution is probably slower now than formerly—Reasons for so thinking—Organic evolution approaching completion—Other supposed objections	[265]
Origin of beauty—Explanation of, in higher animals—In flowering plants—But in many cases we can’t explain	[269]
Incipient organs—Difficulty of explaining—But these are not objections to the fact of evolution, but only to the sufficiency of the present theories of evolution. Therefore, all discussion concerns special theories. The fact of evolution is certain	[270]
[PART III.]
THE RELATION OF EVOLUTION TO RELIGIOUS THOUGHT.
[CHAPTER I.]
INTRODUCTORY.
Evolution if true affects every department of thought—What will be its effect on religious beliefs?—Objection that truth-seeker has nothing to do with effects—Answered	[275]
Relation of the true and the good	[277]
Relation of philosophy to life—The three necessary elements of a rational philosophy—Application to the case in hand—And the subject of Part III justified—Exaggerated fears—Different forms of the conflict of science and religion—(1) Heliocentric theory—First effect and final result—(2) Law of gravitation—Effect and result—(3) Antiquity of the earth and cosmos—Effect and result—(4) Antiquity of man—(5) Evolution	[277]
[CHAPTER II.]
THE RELATION OF EVOLUTION TO MATERIALISM.
Supposed identity—Tendency of the age—Evolution does not differ in this regard from other laws of Nature—Absurdity of identification illustrated in many ways—(1) Effect of discovery of process of making—(2) Effect of new form of old truth—(3) Manner in which vexed questions are settled and rational philosophy found—Illustrated—A true philosophy is a reconciliation of partial views—Three possible views of origin of individuals and of species; two one-sided and partial, and the third combining, reconciling, and therefore rational—The only bar to speedy reconciliation is dogmatism—Theological and scientific—The appropriate rebuke for each—Therefore evolution does not differ from other laws in regard to its relation to materialism—Nevertheless, great changes in our traditional beliefs impending—Main changes are notions concerning God, Nature, and man, in their relations to one another	[284]
[CHAPTER III.]
THE RELATION OF GOD TO NATURE.
The issue in regard to this relation stated—The growth of the issue described—The old view of direct relation—The effect of science and the resulting view—The compromise—Destroyed by evolution—The issue forced—The alternative view—Immanence of Deity—This view explained—Objection of idealism—Answered—It is not subjective idealism—Objection of pantheism—Answer deferred—Objection that the view is incompatible with practical life—Answered	[297]
[CHAPTER IV.]
THE RELATION OF MAN TO NATURE.
The two extreme views in this regard—They are views from different points, psychical and material—The latter very productive in modern times—But many fear the final effect—Reconciliation is possible—Scientific materialism has two branches—Physiological branch explained—Conclusion—Answer—Relation of psychic to brain changes is inscrutable—The mystery illustrated—Outside and inside view—Different from other phenomena in this regard	[304]
Evolution branch—Close relation of man to animals—Therefore must extend immortal spirit to animals—to plants—to all existence, and thus identify immortality with conservation of force—Embryonic series—Where did spirit enter?—Evolution series—Where did spirit enter?—Answer—Derived from Nature—The true view of origin stated—Show that it is not in discord with other phenomena of evolution—The five planes of matter and of force—The change from one to another not gradual now nor in the evolution of natural forces—Consecutive births into higher forms—Every step of these changes taking place now—Relation of these facts to immortality—The process briefly stated—Omnipresent divine energy individuated to separate entity in man—Anima of animals is spirit in embryo—Came to birth in man—Illustrated in other ways—(1) By more or less completed water-drop—(2) By submergence and emergence—(3) By planet birth—(4) By physical birth—(5) By grades of organic individuality—(6) By the body as an instrument of communication between two worlds—Self-consciousness the sign of spirit-individuality—Any animal conscious of self would be immortal—Similar changes in passing from animals to man in all other departments of psychic activity—Objection that other changes of energy not permanent; answered—Our view of origin compared with alternative views—Plato’s view—Orthodox view	[311]
Some general conclusions—(1) Two series of changes, brain-changes and mind-changes—The initiative in animals—In man—(2) Justification of term “vital principle”—Becomes entity in man—(3) This view is a complete reconciliation of realism and nominalism—(4) No meaning in Nature without spirit—And no meaning in geological history without derivative origin of spirit—Material evolution finds its goal in man, psychic evolution in the divine man	[327]
[CHAPTER V.]
THE RELATION OF GOD TO MAN.
Question of revelation—Difficulty of the subject—Operation of divine spirit on spirit of man more direct than on Nature—This is revelation—This is no violation of law, but operation by higher law—Term supernatural is relative—Illustrated—There is but one kind of revelation, and this to all men in different degrees—Always imperfect, and therefore must be tried by reason	[331]
[CHAPTER VI.]
THE OBJECTION, THAT THE ABOVE VIEW IMPLIES PANTHEISM, ANSWERED.
The objection stated and the general answer—In deepest questions single lines of thought lead to extreme views—Must follow other lines—These lead to personality	[335]
(1) Exact character of relation of God and of necessary law to man’s freedom is inscrutable	[338]
(2) On the inside of brain-changes we find personality—So on the inside of natural phenomena must also be person—In either case science studies the outside only—In Nature all is mechanics on the outside, but all is mind on the inside—Thought behind brain-changes compels belief in same behind natural phenomena—Law of infinite expansion—Illustrated by ideas of Space and Time—So also with idea of self—Infinite person inconceivable, but contrary is more inconceivable—Illustrated by ideas of Space and Time	[338]
(3) Idea of Causation and of Force—Derived from within—Steps of the evolution of this idea—Final result is one infinite personal will—Expansion of idea of causal nexus between phenomena to the idea of one infinite cause	[342]
(4) Idea of design also originates within—Ineradicable, but changes form—Expands to infinity—Same change produced by science in all our notions concerning God—Same in our sense of mystery—Same in our notions concerning creation—Same in our conceptions of design—Thus, self-consciousness behind brain-changes compels belief in God behind Nature—The closeness of connection in the one case necessitates closeness of connection in the other—Every material change in Nature caused by a mental change behind Nature	[345]
[CHAPTER VII.]
SOME LOGICAL CONSEQUENCES OF THE DOCTRINE OF THE DIVINE IMMANENCY.
Religious thought subject to the law of evolution; three main stages 351
I. Conception of God—The three stages shown—(1) Anthropomorphism—(2) Absentee landlordism—(3) Immanence	[351]
II. Question of First and Second Causes—The three stages shown here—(1) All is First Cause but man-like—(2) Distinction of first and second causes introduced—(3) Identification of these	[354]
III. General and Special Providence—The same three stages shown and the same outcome—viz., identification	[355]
IV. Natural and the supernatural—The same stages and the same final identification—Question of miracles	[355]
V. Question of design or mind in Nature—The same three stages and the same solution shown here—Confusion in the minds of modern writers	[357]
VI. Question of mode of creation—Old and new views contrasted	[358]
[CHAPTER VIII.]
RELATION OF EVOLUTION TO THE IDEA OF THE CHRIST.
Comparison of organic with human evolution—The idea of the first is man, of the second is the Christ—Definition of the Christ as ideal man—The Christ ought to differ from us in a superhuman way—Shown by several illustrations—The Christ, as ideal man, a true object of rational worship—The ideal of organic evolution comes at the end—Ideal of human evolution must come in the course—Objection that there are many partial ideals answered—Relative vs. absolute moral ideal.	[360]
[CHAPTER IX.]
THE RELATION OF EVOLUTION TO THE PROBLEM OF EVIL.
The difficulty of the problem—The light on it by evolution—Evil must be based on the constitution of Nature and therefore universal—Some of its forms	[365]
(1) Physical evil in animal kingdom—Condition of organic evolution is struggle with an apparently inimical environment—In its course it seems evil—Looking back from the end it is good.	[365]
(2) Physical evil in relation to man—Necessary condition of social evolution is also struggle with a seeming evil environment—But looking back from the end this evil is also seen to be good—Without it man would never have emerged from animality.	[366]
(3) Organic evil—Disease—This also is the necessary condition of acquisition of knowledge of organic Nature—In the course of evolution it seems evil, but from the end it is seen to be good—In the physical world, laws of Nature are beneficent in their general operation, and only evil in their specific operation through our ignorance.	[367]
(4) Moral evil—Moral disease—Difference between this and other forms of evil—Can this also be transmuted into good?—This is only the highest form of evil, and therefore subject to the same laws of evolution—Here also elevation comes only through knowledge and power, and these only through struggle with apparent evil—In course it seems evil, looking back from end it is seen to be good to the race—In all, therefore, the individual is sacrificed to the race, but impossible here—A way of escape found in the nature of a moral being—In this case not only final victory for the race, but also within the power of the individual—In this case success is in proportion to honest effort in right spirit—Roots, of evil in the necessary law of evolution—It is the necessary condition of all progress—Without it a moral being is impossible—From philosophic point of view things are not good and evil, but only higher and lower—All things good in their places—Evil is discord—Good is due relation—Action and reaction of higher and lower is the necessary condition of true virtue	[369]

PART I.
WHAT IS EVOLUTION?

CHAPTER I.
ITS SCOPE AND DEFINITION.

A Type of Evolution.—Every one is familiar with the main facts connected with the development of an egg. We all know that it begins as a microscopic germ-cell, then grows into an egg, then organizes into a chick, and finally grows into a cock; and that the whole process follows some general, well-recognized law. Now, this process is evolution. It is more—it is the type of all evolution. It is that from which we get our idea of evolution, and without which there would be no such word. Whenever and wherever we find a process of change more or less resembling this, and following laws similar to those determining the development of an egg, we call it evolution.

Universality of Evolution.—Evolution as a process is not confined to one thing, the egg, nor as a doctrine is it confined to one department of science—biology. The process pervades the whole universe, and the doctrine concerns alike every department of science—yea, every department of human thought. It is literally one half of all science. Therefore, its truth or falseness, its acceptance or rejection, is no trifling matter, affecting only one small corner of the thought-realm. On the contrary, it affects profoundly the foundations of philosophy, and therefore the whole domain of thought. It determines the whole attitude of the mind toward Nature and God.

I have said evolution constitutes one half of all science. This may seem to some a startling proposition. I stop to make it good.

Every system of correlated parts may be studied from two points of view, which give rise to two departments of science, one of which—and the greater and more complex—is evolution. The one concerns changes within the system by action and reaction between the parts, producing equilibrium and stability; the other concerns the progressive movement of the system, as a whole, to higher and higher conditions—the movement of the point of equilibrium itself, by constant slight disturbance and readjustment of parts on a higher plane, with more complex inter-relations. The one concerns the laws of sustentation of the system, the other the laws of evolution. The one concerns things as they are, the other the process by which they become so. Now, Nature as a whole is such a system of correlated parts. Every department and sub-department of Nature, whether it be the solar system or the earth, or the organic kingdom, or human society, or the human body, is such a system of correlated parts, and is therefore subject to evolution. We can best make this thought clear by examples:

1. Take, then, the human body. This complex and beautiful system of correlated and nicely-adjusted parts may be studied in a state of maturity and equilibrium, in which all the organs and functions by action and reaction co-operate to produce perfect stability, health, and physical happiness. This study is physiology. Or else the same may be studied in a state of progressive change. Now, we perceive that the stability is never perfect—the point of equilibrium is ever moving. By the ever-changing number and relative power of the co-operating parts the equilibrium is ever being disturbed, only to be readjusted on a higher plane, with still more beautiful and complex inter-relations. This is growth, development, evolution. Its study is called embryology. 2. Take another example—the solar system. We may study sun, planets, and satellites in their mutual actions and reactions, co-operating to produce perfect equilibrium, stability, beautiful order, and musical harmony. This is the ideal of physical astronomy as embodied in Laplace’s “Mécanique Céleste.” Or we may study the same in its origin and progressive change. Now, we perceive that equilibrium and stability are never absolutely perfect, but, on the contrary, there is continual disturbance with readjustment on a higher plane—continual introduction of infinitesimal discord, only to enhance the grandeur and complexity of the harmonic relations. This is the nebular hypothesis—the theory of the development of the solar system. It is cosmogony; it is evolution. 3. Again: society may be studied in the mutual play of all its social functions so adjusted as to produce social equilibrium, happiness, prosperity, and good government. This is social statics. But equilibrium and stability are never perfect. Permanent social equilibrium would be social stagnation and decay. Therefore, we must study society also in its onward movement—the equilibrium ever disturbed, only to be readjusted on a higher plane with more and more complexly inter-related parts. This is dynamics—social progress. It is evolution. 4. Again: the earth, as a whole, may be studied in its present forms, and the mutual action of all its parts—lands and seas, mountains and valleys, rivers, gulfs, and bays, currents of air and ocean—and the manner in which all these, by action and reaction, co-operate to produce climates and physical conditions such as we now find them. This is physical geography. Or, we may study the earth in its gradual progress toward its present condition—the changes which have taken place in all these parts, and consequent changes in climate; in a word, the gradual process of becoming what it now is. This is physical geology—it is evolution. 5. Lastly, we may study the whole organic kingdom in its entirety as we now find it—the mutual relation of different classes, orders, genera, and species to each other and to external conditions, and the action and reaction of these in the struggle for life—the geographical distribution of species and their relation to climate and other physical conditions, the whole constituting a complexly adjusted and permanent equilibrium. This is a science of great importance, but one not yet distinctly conceived, much less named.[1] Or, we may study the same in its gradual progressive approach, throughout all geological times, toward the present condition of things, by continual changes in the parts, and therefore disturbance of equilibrium and readjustment on a higher plane with more complex inter-relations. This is development of the organic kingdom. In the popular mind it is, par excellence, evolution.

We might multiply examples without limit. There are the same two points of view on all subjects. As already said, in the one we are concerned with things as they are; in the other, with the process by which they became so. This “law of becoming” in all things—this universal law of progressive inter-connected change—may be called the law of continuity. We all recognize the universal relation of things, gravitative or other, in space. This asserts the universal causal relation of things in time. This is the universal law of evolution.

But it has so happened that in the popular mind the term evolution is mostly confined to the development of the organic kingdom, or the law of continuity as applied to this department of Nature. The reason of this is that this department was the last to acknowledge the supremacy of this law; this is the domain in which the advocates of supernaturalism in the realm of Nature had made their last stand. But it is wholly unphilosophical thus to limit the term. If there be any evolution, par excellence, it is evolution of the individual or embryonic development. This is the clearest, the most familiar, and most easily understood, and therefore the type of evolution. We first take our idea of evolution from this form, and then extend it to other forms of continuous change following a similar law. But, since the popular mind limits the term to development of the organic kingdom, and since, moreover, this is now the battleground between the advocates of continuity and discontinuity—of naturalism and supernaturalism in the realm of Nature—what we shall say will have reference chiefly to this department, though we shall illustrate freely by reference to other forms of evolution.

EVOLUTIONITS NATURE, ITS EVIDENCES, AND ITSRELATION TO RELIGIOUS THOUGHT