SUGGESTIBILITY AND KINDRED PHENOMENA. 377 



to awaken one another. This is what is commonly described as 

 association of ideas. The reverse is also true, although not as well 

 known; many states tend to prevent the appearance of other 

 states. Agreeable states, for example, tend to force out the disa- 

 greeable, and vice versa. This, then, may be generalized in the 

 statement of the second property of mental states : every mental 

 state tends to produce, or prevent the production of, other states. 

 We may suppose that these phenomena are due to the interplay of 

 systems of activities within the cortex with one another. 



But these activities within the cortex which underlie our ordi- 

 nary life of sensation and thought tend also to discharge down- 

 ward through the Rolandic region into the motor mechanism, 

 producing contractions of the muscles. Thus the third property 

 of the mental state is the ability to produce or prevent muscular 

 contraction. Not all mental states have this property in the same 

 degree. It is most evidently true of the feeling of movement. I 

 once asked a class of sixteen girls to think intently what it would 

 feel like to lift the right hand and touch the left shoulder. After 

 a few minutes had elapsed nine of them confessed having felt a 

 desire to do it. I then dropped the subject and spoke of some- 

 thing else : in a few moments six actually did it. Most .persons 

 when concentrating attention upon the thought of what a given 

 movement would feel like, find themselves becoming possessed 

 of a desire to do it, and this desire marks the tendency of the 

 thought to produce the movement. But as we not only feel but 

 also see our movements, we find that the thought of what a move- 

 ment looks like has also motor value and tends to produce it. 

 This is also true of touches and ideas of touch indeed, all or 

 nearly all mental states produce some motor changes in the body, 

 but the motor effects of sensations and ideas of sound, taste, and 

 smell are relatively slight. 



Again, mental states tend to help or hinder the processes of 

 secretion and nutrition. We all know that the secretions of the 

 salivary glands, of the kidneys, of the mammary, and other glands 

 are readily affected by many mental states, but their effect upon the 

 processes of nutrition is more disputed. It is quite certain that 

 in a general way the impulses sent out by the central nervous 

 system are necessary to the proper nutrition of the body, but it is 

 not as generally accepted that individual mental states can pro- 

 duce definite changes, as/for example, when it is reported that a 

 hypnotized patient, by thinking of a burn, has actually produced 

 the burn. Yet even for this there is good evidence. 



One may justly ask how it is, if mental states really have defi- 

 nite consequences, that we fail to note in our mental life the 

 orderly sequence of cause and effect with which we are familiar 

 in the physical world ? If there be any truth in the theory above 



VOL. XLVIII. 27 



