ix PSYCHO-PHYSICAL PHENOMENA 439 



consciousness in other words, acquire a subjective aspect and 

 present themselves to introspection. The greater part of the 

 elementary nervous activities, which consist in simple responsive 

 or reflex acts, fulfil their protective or regulatory functions in 

 the body within the region of the unconscious. This can be 

 observed not only in all the nervous actions destined to influence 

 and control the functions of the visceral organs, but also in a great 

 number of the excitations that affect the organs of animal life. 

 During the activity of the senses, again, the psycho-physical 

 phenomena, the physiological processes that reach consciousness, 

 include only a small part of those in which the sensory system is 

 concerned, those, namely, which are the object of attention. So 

 that in our nervous system the unconscious and the conscious are 

 very unequally divided ; the neural excitations presented to intro- 

 spection as part of the ego are few in number, and do not 

 permanently occupy the same position, but are constantly dis- 

 placed according to the direction of attention and the current of 

 thought. Whatever remains outside the focus of attention is 

 not clearly apperceived, and may be provisorily regarded as 

 unconscious. So that if the mind consisted exclusively of the 

 sum of the phenomena of which we are fully conscious, the 

 province and scope of our mental life would be poor and narrow 

 indeed. 



But when we come to examine the nervous processes that do 

 not reach consciousness, it is evident that they depend in many 

 cases on the same complex mechanisms as those that become 

 conscious, and have the same specific characters. When, for 

 instance, we walk along a road, completely absorbed in what we 

 are going to say to the person we are about to visit, the locomotor 

 mechanism carries out its functions perfectly without assistance 

 from our will or consciousness. But our movements, guided more 

 especially by sight, are not entirely comparable to a regular series 

 of simple reflex actions, because they are continually altered and 

 modified in order to avoid obstacles, such as vehicles and people 

 on the road ; in a word, we adapt our muscular acts, according to 

 circumstances, to the end we have in view. The same applies to 

 an expert violinist who is executing a piece of music. While his 

 attention is wholly absorbed in the current of multiple auditory 

 sensations combined in successive order, his eyes glance rapidly 

 down the page, without waiting to perceive the individual notes, 

 and his hands automatically and unconsciously perform a long 

 series of varied movements, of a complicated and difficult kind, 

 co-ordinated to produce an artistic effect with the minutest 

 gradations of tone, intensity, and musical expression. 



Now the only possible scientific criterion by which we are 

 able objectively to distinguish psychical manifestations from purely 

 mechanical phenomena is their perseverance in an aim, their 



