it may.

his innermost conviction; leaving it to produce what effect It is not for nothing that he has in him these sympathies with some principles and repugnance to others. He, with all his capacities, and aspirations, and beliefs, is not an accident but a product of the time. While he is a descendant of the past he is a parent of the future; and his thoughts are as children born to him, which he may not carelessly let die. Like every other man he may properly consider himself as one of the myriad agencies through whom works the Unknown Cause; and when the Unknown Cause produces in him a certain belief, he is thereby authorized to profess and act out that belief. . . . Not as adventitious therefore will the wise man regard the faith that is in him. The highest truth he sees he will fearlessly utter; knowing that, let what may come of it, he is thus playing his right part in the world —knowing that if he can effect the change he aims at—well; if not-well also; though not so well.

IV. BIOLOGY: THE EVOLUTION OF LIFE

The second and third volumes of the Synthetic Philosophy appeared in 1872 under the title of Principles of Biology. They revealed the natural limitations of a philosopher invading a specialist's field; but they atoned for errors of detail by illuminating generalizations that gave a new unity and intelligibility to vast areas of biological fact.

Spencer begins with a famous definition: "Life is the continuous adjustment of internal relations to external relations." 1 The completeness of life depends on the completeness of this correspondence; and life is perfect when the correspondence is perfect. The correspondence is not a merely passive adaptation; what distinguishes life is the adjustment of internal relations in anticipation of a change in external relations, as when an animal crouches to avoid a blow, or a man makes a fire to warm his food. The defect of the definition lies not merely in its tendency to neglect the 1 Principles of Biology; New York, 1910; 1, 99.

remoulding activity of the organism upon the environment, but in its failure to explain what is that subtle power whereby an organism is enabled to make these prophetic adjustments that characterize vitality. In a chapter added to later editions, Spencer was forced to discuss "The Dynamic Element in Life," and to admit that his definition had not really revealed the nature of life. "We are obliged to confess that Life in its essence cannot be conceived in physico-chemical terms." 1 He did not realize how damaging such an admission was to the unity and completeness of his system.

As Spencer sees in the life of the individual an adjustment of internal to external relations, so he sees in the life of the species a remarkable adjustment of reproductive fertility to the conditions of its habitat. Reproduction arises originally as a readaptation of the nutritive surface to the nourished mass; the growth of an amoeba, for example, involves an increase of mass much more rapid than the increase in the surface through which the mass must get its nourishment. Division, budding, spore-formation, and sexual reproduction have this in common, that the ratio of mass to surface is reduced, and the nutritive balance is restored. Hence the growth of the individual organism beyond a certain point is dangerous; and normally growth gives way, after a time, to reproduction.

On the average, growth varies inversely with the rate of energy-expenditure; and the rate of reproduction varies inversely with the degree of growth. "It is well known to breeders that if a filly is allowed to bear a foal, she is thereby prevented from reaching her proper size. . . . As a converse fact, castrated animals, as capons and notably cats, often become larger than their unmutilated associates." 2 The rate of reproduction tends to fall as the development and capability of the individual progress. "When, from lowness of organization, the ability to contend with external dangers

1 I, 120.

2 II, 459.

is small, there must be great fertility to compensate for the consequent mortality; otherwise the race must die out. When, on the contrary, high endowments give much capacity for self-preservation, a correspondingly low degree of fertility is requisite," lest the rate of multiplication should outrun the supply of food.1 In general, then, there is an opposition of individuation and genesis, or individual development and fertility. The rule holds for groups and species more regularly than for individuals: the more highly developed the species or the group, the lower will its birth-rate be. But it holds for individuals too, on the average. For example, intellectual development seems hostile to fertility. "Where exceptional fertility exists, there is sluggishness of mind, and where there has been, during education, excessive expenditure in mental action, there frequently follows a complete or partial infertility. Hence the particular kind of further evolution which Man is hereafter to undergo is one which, more than any other, may be expected to cause a decline in his power of reproduction." 2 Philosophers are notorious for shirking parentage. In woman, on the other hand, the arrival of motherhood normally brings a diminution of intellectual activity; and perhaps her shorter adolescence is due to her earlier sacrifice to reproduction.

3

Despite this approximate adaptation of birth-rate to the needs of group survival, the adaptation is never complete, and Malthus was right in his general principle that population tends to outrun the means of subsistence. "From the beginning this pressure of population has been the proximate cause of progress. It produced the original diffusion of the race. It compelled men to abandon predatory habits and take to agriculture. It led to the clearing of the earth's surface. It forced men into the social state, . . . and developed the social sentiments. It has stimulated to progressive improve

1 II, 421.

2 II, 530.

3 Autob., i, 62.

ments in production, and to increased skill and intelligence.” 1 It is the chief cause of that struggle for existence through which the fittest are enabled to survive, and through which the level of the race is raised.

Whether the arrival of the fittest is due chiefly to spontaneous favorable variations, or to the partial inheritance of characters or capacities repeatedly acquired by successive generations, is a question on which Spencer took no dogmatic stand; he accepted Darwin's theory gladly, but felt that there were facts which it could not explain, and which compelled a modified acceptance of Lamarckian views. He defended Lamarck with fine vigor in his controversy with Weismann, and pointed out certain defects in the Darwinian theory. In those days Spencer stood almost alone on the side of Lamarck; it is of some interest to note that today the neo-Lamarckians include descendants of Darwin, while the greatest contemporary English biologist gives it as the view of present-day students of genetics that Darwin's particular theory (not, of course the general theory) of evolution must be abandoned.2

V. PSYCHOLOGY: THE EVOLUTION OF MIND

The two volumes on The Principles of Psychology (1873) are the weakest links in Spencer's chain. There had been an earlier volume on the subject (1855), a youthfully vigorous defense of materialism and determinism; but age and thought revised this into a milder form, and padded it out with hundreds of pages of painstaking but unilluminating analysis. Here, even more than elsewhere, Spencer is rich in theories and poor in proofs. He has a theory of the origin of nerves out of intercellular connective tissue; and a theory of the genesis of instinct by the compounding of reflexes and the transmission of acquired characters; and a theory of the origin of mental categories out of the experience of the race; and 1 Biology, ii, 536.

2 Cf., address of Sir Wm. Bateson before the American Association for the Advancement of Science (Toronto, Dec. 28, 1921), in Science, Jan. 20, 1922.

1

a theory of "transfigured realism"; 1 and a hundred other theories that have all the obfuscating power of metaphysics rather than the clarifying virtue of a matter-of-fact psychology. In these volumes we leave realistic England and go "back to Kant.”

What strikes us at once is that for the first time in the history of psychology, we get here a resolutely evolutionist point of view, an attempt at genetic explanations, an effort to trace the bewildering complexities of thought down to the simplest of nervous operations, and finally to the motions of matter. It is true that this effort fails; but who has ever succeeded in such an attempt? Spencer sets out with a magnificent program for the unveiling of the processes whereby consciousness has been evolved; in the end he is compelled to posit consciousness everywhere,2 in order to evolve it. He insists that there has been one continuous evolution from nebula to mind, and at last confesses that matter is known only through mind. Perhaps the most significant paragraphs in these volumes are those in which the materialist philosophy is abandoned:

Can the oscillation of a molecule be represented in consciousness side by side with a nervous shock, and the two be recognized as one? No effort enables us to assimilate them. That a unit of feeling has nothing in common with a unit of motion, becomes more than ever manifest when we bring the two into jutaxposition. And the immediate verdict of consciousness thus given, might be analytically justified; . for it might be shown that the conception of an oscillating molecule is built out of many units of feeling." (I. e., our knowledge of matter is built up out of units of mind—sensations and memories and ideas). Were we compelled to choose between the alternatives of translating mental phenomena into physical phenomena, or of translating physi

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1 Spencer means by this that although the objects of experience may very well be transfigured by perception, and be quite other than they seem, they have an existence which does not all depend upon perceiving them.-II, 494. 2 Autob., ii, 549.