§ 15. The Sociological Factor in Psychology. In the second place, the psychologist's reference to the external conditions of mental activity and mental development must include not only the bodily organism and even the objects of the physical environment which act upon this, and through it on the mind, but also that social environment or community in interaction with which the individual thinks and acts. We cannot understand an individual human mind in abstract separation from the community of minds. Each of us feels, thinks and acts as he does under the constant influence of social relations. The human mind is human, that is, superior to the animal mind, just because of the reciprocal action of mind on mind in social life. Thus, to understand human thought we must consider its necessary accompaniment, language, and view this as the outcome of social needs and impulses (the need of mutual expression and understanding). The highest manifestations of mind, e.g., the fully developed conscience, are essentially the product of that sum of social conditions which we call civilisation. The individual is enriched by the race, not merely by means of a hereditary transmission of some of the results of its experience, but to a far larger extent by means of social traditions, and all that we call the education of the individual by the community. Hence to understand the growth of a mind we must refer to those processes of sociological evolution and historical progress by which this sum of traditional and educative influences has been established. In other words, we must study mind by what has been called "the historical method".

It is in this more complete and historical study of the human mind that the knowledge of the psychical characteristics of backward races acquires its main value for the psychologist. It is by a study of the cruder manifestations of mind in primitive man and his living representatives that we come to see what social evolution and the traditional influences involved in a civilised community effect in furthering the intellectual, emotional and moral development of the individual.

The recognition of a "sociological factor" in psychology raises the question as to the true relation of psychology and sociology. As commonly understood, e.g., by J. S. Mill, psychology necessarily precedes sociology: we must understand the laws of the individual mind before we can understand the more complex phenomena resulting from the interaction of mind on mind in a social community, such as the

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moral sense. At the same time more recent writers, and especially G. H. Lewes, have insisted on the necessity of taking into account the sociological factor in studying the development of the individual mind.

A reconciliation of these views may perhaps be found in distinguishing the more abstract principles of psychology from their concrete applications in explaining the actual development of the typical mind. The former, for example the laws which govern the formation of ideas in general, can be reached without any reference to the 'social organism,' and by a purely abstract consideration of the individual mind. On the other hand, to account for the actual forms of the mental life as it shows itself in civilised man, we must, it is evident, pay regard to social conditions. The ideas, the emotions, and the conduct of the individual at our present stage of social evolution are determined by the past stages of this social evolution. To understand this action of one mind on another, the mind of the community on that of the individual, we must, it is true, make use of purely psychological laws gained by an abstract consideration of the processes of the individual mind. In other words, any effect of social circumstances in furthering the development of the individual mind, e.g., of social custom in forming ideas of what is right, must conform to and illustrate the universal laws of psychical development. And to this extent psychology it undoubtedly prior to sociology. Nevertheless it is true that the psychologist must assume these social circumstances and forces among his data if he is to attempt to deal with the processes of the individual mental life in any other than the most abstract and fruitless manner.1

REFERENCES FOR READING.

On the whole subject of the Method of Psychology see J. S. Mill, Logic, bk. vi. chap. vi.; Lewes, Study of Psychology, chap. iv. and following; Bain, Logic: Induction, bk. v. chap. v.; Brentano, Psychologie, buch i. cap. ii. to iv.; James, Principles of Psychology, chap. vii.

1 On the relation of psychology to sociology see J. S. Mill, Logic, bk. vi. chap. vi.; G. H. Lewes, Problems of Life and Mind, third series, i. (The Study of Psychology), chap. iv., cf. first series, vol i. p. 152; and Prof. H. Sidgwick, Mind, vol. xi. (1886) p. 211 and following.

CHAPTER III.

PHYSICAL BASIS OF MENTAL LIFE.

§ 1. Phenomenal Connexion of Mind and Body. As pointed out above, a very slight examination of the processes making up our conscious mental life suffices to show that they are closely conjoined with that sum of physical actions which constitutes the life of the body. The science of psychology has to take note of this connexion, and to present it in the clearest light possible. In doing this it views the relation merely as a connexion of phenomena, viz., of physical movements and mental processes running on concomitantly in time. It does not raise the question how it comes to pass that these two radically dissimilar modes of activity are thus associated, a question which, as we have seen, belongs to metaphysical or rational psychology.

§ 2. Range of Interaction of Mind and Body. A hasty and superficial observation might suggest that all parts of the physical organism are directly connected with our mental life. Thus an injury to any one of the bodily structures, except the insensitive portions, the hair, nails, etc., gives rise to a feeling of pain. So again our mental states produce effects throughout the bodily frame. Great mental agitation, for example, affects the breathing, the circulation, and so forth. We seem too to be able, by an effort of attention, to get into mental touch with any part of the body, making it the object of direct mental apprehension through certain localised sensations, as when we concentrate attention on the breathing apparatus or one of the fingers.

Yet further inquiry soon shows that this connexion of mind with body is not equally close throughout. Thus it is evident that the vital functions, which minister to the maintenance of

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the organism, as digestion, circulation, etc., are but loosely and remotely connected with consciousness. Under healthy conditions these vegetative functions of the body affect mind only on its dim sub-conscious side, contributing psychical elements in the shape of a pleasurable sense of well-being. Orly serious disturbances of these functions produce marked and distinct psychical effects. And conversely it is only certain exceptional forms of mental activity, and more especially emotional excitement, which modify in a clear and striking manner these vital actions.

If now we turn from these organs of the vegetative life to those which subserve distinctly animal functions we find a much closer union with mental activity. Thus the structures which most obviously subserve movement and sensation, viz., the muscular organs and the organs of sense, as the eye, the ear, etc., seem to be very closely connected with the higher strata of mental life, viz., clear consciousness. Under normal circumstances our limbs are never moved save in obedience to a voluntary command. And the activities of the senseorgans are the chief occasion of mental activity, at least in its earlier forms, such as the perception and comparison of external objects.

§3. Special Organs of Mind. Even here, however, further reflexion makes it evident that the connexion is not immediate and constant. We can reflect, reason, and so forth, when both the organs of sense and those of movement are apparently inactive. In sleep the mental life may continue under the form of dreaming without any co-operation from these organs. They thus seem to be the exterior mechanism by which the mind occasionally puts itself en rapport with the external world, not the organs whose activity directly sustains the flow of consciousness. Such an organ of mind or "seat of the soul" would seem to be rather in some central, as distinguished from peripheral, region of the body. And, indeed, we find that already in an early stage of human thought such a seat was assigned to the soul, sometimes in the heart, at other times in the head. These vague conjectures have been rendered definite and precise by the discoveries of the modern science of physiology. We now know that there are certain organs of the body constituting in their ensemble the Nervous System which spe

cially subserve the processes of our mental life. This system supplies in the centres of the Brain a definite substratum or seat' of mental activity. Moreover, since it stands in close connexion with the organs of sense and movement we are able to explain by means of it the indirect connexion between these and mental activity. Finally, inasmuch as it has ramifications in all parts of the body we can by its help account for the far-reaching interaction and sympathy of mind and body.

§ 3a. History of Views on the Bodily Seat of the Soul. The history of the attempt to find a special organ or seat of mental activity in the body forms one of the most curious chapters in the development of human thought. At the outset when man could not form a clear idea of mind as something non-material, it was, as we have seen, specially identified with the breath or warm air (Tveûμa) which circulated throughout the body and was at once the source of heat and activity. According to this view the soul was diffused throughout the organism. At the same time we see a tendency to assign special centres to mental activity. Thus we find in Homer the heart figuring as the seat of the mind's passions. The idea of a special connexion between the heart and the mental life which still survives in popular language was supported in part by the doctrine of veûμa, the warm air being supposed (even by Aristotle) to be developed out of the blood, and partly no doubt by the observed effects of strong emotion on that organ. Plato, in his scheme of mind, referred the inferior operations to the abdomen and the thorax, reserving the cranium for reason. But, the nerves not having been discovered, he seems to have thought that impressions were transmitted to the brain by the blood. vessels. Hence we need not be surprised at finding Aristotle rejecting the cranium as the seat of mind, and referring it to the heart. The stubborn persistence of the old doctrine of aveûμa is curiously illustrated in the fact that even so late a writer as Galen thought the warm air in the ventricles of the brain constituted the true seat of mental activity. It is only through the stricter methods of physiological research adopted in modern times that we have come to understand the real nature of the connexion between mind and body as mediated by the mechanism of the Nervous System. This improved modern research includes a more careful anatomy of the finer structures of the body, a more extended comparison of their variations in different species of animals (comparative anatomy), fuller medical knowledge of the effects of injuries to the nervous structures, and lastly, carefully arranged experiments with a view to discover the precise functions of the several bodily structures.1

1 On the historical developments of our knowledge of the physical basis of mind, see Siebeck, Geschichte der Psychologie, i. 207, ii. 46, 130 seq., and 266 seq.; cf. Whewell, History of Inductive Sciences, bk. xvii. ch. i. and ch. v. The complicated process of inference by which each of us comes to connect his own states of consciousness with a nervous system in his own body of which he has no direct knowledge, is well described by Mr. Spencer, Principles of Psychology, pt. i. ch. vi. (Estho-physiology).