so HABIT AND INTELLIGENCE. [chap. 



believe that all currents of consciousness are secondary- 

 currents ; those of original consciousness are excited by 

 currents of sensation (though, as we have seen, they 

 sometimes outlast their exciting cause) ; those of repro- 

 duced consciousness are excited by currents of thought. 

 Currents of thought, both in exciting one another and in 

 exciting currents of consciousness, act according to the 

 law of mental habit, or, as it is usually called, the law of 

 the association of ideas ; of which I shall have to speak 

 in a future chapter. 

 Consen- j^ many cases, remembered consciousness acts on the 



sual action ^ > 



produced motor nerves, and on the whole organism, exactly as the 

 bered"cou-" oi"igiii^l sensation, or the consciousness of it, would do. 

 sciousness. The thought of a disgusting object, for instance, sometimes 

 produces nausea. Dr. Carpenter mentions an instance of 

 sea-sickness being brought on by the sight of a ship 

 tossing on a stormy sea. Such cases are to be regarded 

 as cases of consensual action — due, however, to reproduced 

 consciousness, not to sensation or the original consciousness 

 of sensation. Dr. Carpenter proposes to call these ideo- 

 motor actions ; indicating by this word that they are set 

 going, not by a sensation, but by the revived consciousness, 

 or idea, of a sensation. 



In order, so far as it is possible, to complete the physio- 

 logical theory of the mind which I am here attempting, it 

 now only remains to speak of voluntary action. 

 Voluntary Voluntary action is related to consensual action, in the 

 action. same way that recollection, or reproduced consciousness, is 

 related to original consciousness. As I have already stated 

 my belief on the subject, the consciousness of a sensation 

 is due to a nerve-current of consciousness being excited 

 by the nerve-current of sensation ; and the recollection, 

 or revived consciousness, of the same sensation is due 

 to a similar nerve-current of consciousness being excited 

 by a nerve-current of thought. Thus, when I remember 

 to-day the speech I heard yesterday, the revived con- 

 sciousness of the sounds is just like the original conscious- 

 ness I had of them when I heard them, only fainter; 

 but the currents of consciousness were then excited by 



