260 Mr. Victor Horsley [March 27, 



over the object, that as soon as another object is brought to us our 

 attention is distracted, that is to say, turned aside. 



All writers are agreed that the attention cannot be divided, that 

 we really only attend to one thing at once. 



It seems to me that this is so obvious as not to require experi- 

 mental demonstration, but I have led up to this point because I now 

 wish to refer to the third part of my subject, namely, the question as 

 to whether we have a really double nervous system or not ; but by 

 way of preface let me repeat that although we may have a subcon- 

 sciousness of objects and acts, that that subconscious state is true 

 automatism, and that such automatic acts are in no sense voluntary 

 until the attention has been concentrated upon them. For example, 

 again I press this tambour because I desire to raise the flag, and I 

 keep that raised while I attend to what I am saying to you. My 

 action of keeping the flag raised is only present to my consciousness 

 in a slight or subordinate degree, and does not require my attontion, , 

 deliberate thought or choice, and therefore I repeat is not a voluntary 

 action, in fact it could be carried on perfectly well by this lower 

 sensori motor centre, which only now and then sends up a message to 

 say it is doing its duty, in the same way as a sentry calls out " All 

 well " at intervals. 



But to return. In consequence of the obvious fact that we have 

 two nerve organs, each more or less complete, some writers have 

 imagined that we have two minds ; and to the Rev. Mr. Barlow, a 

 former Secretary of this Institution, is due the credit of recognising 

 the circumstances which seem to favour that view. It was keenly 

 taken up, and the furor culminated in a German writer (whose name [ 

 am ashamed to say has escaped me) postulating that we possess two 

 souls. 



Now the evidence upon which this notion rests, that the two 

 halves of the brain might occasionally work independently of one 

 another at the same moment, was of two kinds. In the first place it 

 was asserted that we could do two different things at once, and in the 

 second place evidence was produced of people acting and thinking as 

 if they had two minds. 



Now, while of course admitting that habitually one motor centre 

 usually acts at one moment by itself, I am prejiared to deny in toto 

 that two voluntary acts can be performed at the same time, and I have 

 already shown what is necessary for the fulfilment of all the con- 

 ditions of volition, and that these conditions are summed up in the 

 word attention. 



Further, I have already shown tliat when an idea comes into the 

 mind owing to some object catching the eye, that both sensory areas 

 are engaged in considering it. It seems to me I might stop here, and 

 say that here was an a priori reason why two simultaneous voluntary 

 acts are impossible ; but as my statements have mot with some oppo- 

 sition, I prefer to demonstrate the fact by some ex[)eriments. 



The problem, stated in physiological terms, is as follows : 



