of the connection between the movements of the nervous system and brain which are distinctly physical, and the elementary phenomena accompanying or following them which are distinctly mental. The following are clearly distinguished doctrines upon the subject:

(1.) It is held by some that the mind is a function of the brain. In order to understand this, we must bear in mind the relation between function and organ in the vegetable and animal kingdoms. An organ is a constituent part of an organised body which has some definite duty or function to perform. The function of the leg of an animal is to walk or run; that of the wing of a bird is to beat the air so as to enable the bird to fly. The stomach is a large internal organ of the body, whose function is to contain the food which we swallow, until it has been prepared for being taken into the blood. The liver is another organ, whose function is to secrete bile, which is poured into the stomach to assist in the digestion of our food. Every organ has got some special work or function to perform in the body to which it belongs. In the same way, it is argued, the brain has a function to perform in the animal system, and that is to produce the various mental phenomena of which we are conscious. And, acting upon this hasty and crude hypothesis, a set of visionary speculators called phrenologists have thought that they could learn all about the mind, its character, and its laws, by the study of its organ, the brain.*

*This is the theory also of M. Comte, G. H. Lewes, and others,

There are many objections to this hypothesis which might be referred to; but in the mean time we shall point out only one, which, however, will be sufficient to set it aside for the present.

The functions of all the organs with which we are acquainted are perceived by us either as some material product or some mode of motion. We are able to examine both the organ and the function as ordinary physical phenomena; both the organ and the function are made known by perception through the senses. But in the case of the brain, the organ is indeed capable of being examined as we examine any other physical organ-by external observation aided by the employment of the dissecting knife. And if we consider the brain as the centre of nervous force by which the muscles of the body are made to contract, we are able to perceive a function of the brain in its result-ordinary muscular motion. But mental phenomena are directly perceived only by consciousness, and are entirely different in kind from any of the functions of physical organs with which we are acquainted.

Hence there is a strong presumption, which may be confirmed as we advance, against the hypothesis that the relation between the nervous system and the phenomena of the mind is identical with that between ordinary physical organs and their functions. Consequently, although a knowledge of the nervous

who give prominence to the study of physiology as a means of becoming acquainted with mental laws.

CHAP. I.

SECT. II.

CHAP. I.

SECT. II.

(2.) Mind

and body two independent

substances.

9

system may be of importance to the study of mind, we can attach to it at present but a subordinate degree of importance.

(2.) A second theory of the relation between the mind and the body may be described in the following manner. The mind and the body are two entirely different substances possessing entirely different qualities. The mind has been brought into connection with the body, inhabits the body, and uses the body as its instrument of carrying out its purposes and communicating with the external world; but they are in nature so entirely different, that there is, and can be, no truly causal connection between the phenomena of the one and those of the other. An impression upon an organ is only an occasion on which, by some mysterious power, a sensation is produced in the mind. So the occurrence of a volition or determination in the mind is only an occasion on which, by divine interference, a movement is excited in some of the muscles of the body. The connection between the mind and body is only accidental, and might have been otherwise. The one is now inhabiting and employing the other, but has an existence really independent of the other; and our knowledge of the one cannot be increased to any material extent by a study of the other. Those who hold a theory such as this attach very little importance to the study of the brain and nervous system as subordinate to psychology. It is a degradation to the mind. to suppose that any light can be thrown upon its

workings by a study of its humble habitation and instrument. Consciousness, therefore, and consciousness alone should be resorted to by the student of psychology.

A theory such as this was held by the older followers of Descartes and the older adherents of the Scottish philosophical school. But there are certain considerations which will prevent us from adopting it as an hypothesis to guide us in our studies. In the first place, the student of psychology has nothing to do with the so-called substances of mind or matter; he has to study only the phenomena, the sensations and the qualities which consciousness and perception make known to him. And, again, it is unscientific to advance to the study of the mind with certain preformed and crude notions regarding its nature, its independence of matter, and other things. As far as our experience goes, the mind is most intimately connected with our physical organism, and it appears to be the duty of the psychologist to take into account every fact bearing upon his subject, admitted to exist, and learn as much from it as possible. Moreover, it lies within his sphere to study only those phenomena which manifest themselves in our present conditions of existence, and not to speculate or make assertions regarding what might be under other conditions.

(3.) A third theory respecting the connection between physical and mental phenomena regards them as simple antecedents and consequents, without predicating anything concerning the differences in

CHAP. I.

SECT. II.

(3.) Mental

and cere

bral events form two partially co-ordinate

CHAP. I.

SECT. II.

series

whose re

lations are

not accurately known.

their nature except in so far as may be learned from actual observation. A certain physical movement or nervous vibration takes place; it is followed by a sensation. A certain volition is determined in the mind; it is followed by a muscular movement. The psychologist, aided by the physiologist, may legitimately endeavour to discover what particular phenomena of a physical kind always precede or follow certain phenomena of a mental kind, in what order the two series of phenomena occur, and other facts regarding them of a similar kind. But on the other hand, it is not legitimate to assume, without satisfactory reasons, that every mental phenomenon has a physical or nervous antecedent, any more than it is legitimate to take for granted that every organic action is the result of some conscious mental antecedent. As physiologists tell us about certain organic actions which take place in the body altogether independent of any mental determination, so there is an à priori probability that there are mental activities which are not connected with any particular physical movements; and in consequence of this presumption, those who assert the contrary are bound to support their assertions by the evidence of observed facts. The burden of proof falls upon them.

This third theory of the concomitance of the physical and the mental series of phenomena is the one which appears to us nearest the truth as far as we know it. It asserts nothing regarding the relations of mind and matter except what is