CH. LII.] THE PHYSIOLOGY OF CONSCIOUS STATES 759 



outside of ourselves (the object) and our feelings and strivings in 

 connection with it, which are spoken of as subjective. The existence 

 of this " subject-object relation " implies the activity of an Ego, who 

 experiences conscious states, who is cognisant, feels or strives. 

 Indeed no state of consciousness is ever possible, unless experienced 

 by the Ego. In becoming manifest, it blends with the Ego, and is 

 modified or rather determined by the Ego's previous experiences ; 

 and in turn it modifies the Ego. Thus the Ego everlastingly moulds 

 and is itself moulded by its own states of consciousness or 

 experiences. Consequently, states of consciousness are not inde- 

 pendent units. The mind, like its physiological correlate, the central 

 nervous system, works as a single, unitary entity, despite its com- 

 plex differentiation (see also p. 725). 



From one aspect "states" of consciousness is an inaccurate 

 expression. The essential features of consciousness are its incessant 

 change and its intimate relation to past and future consciousness ; 

 whereas the word state implies a period of rest and a certain isolation 

 or independence. Save for this difficulty, it would be possible to 

 regard a given state of consciousness as the cross-section of a stream 

 which is always flowing. The simile may be deemed of value, in so 

 far as it allows us to represent different levels of conscious states. 

 At any moment, there is always part which is in the focus, or full 

 glare of consciousness, and part of which we are dimly conscious or 

 wholly unconscious, but of which we may at any moment become 

 conscious for example, the ticking of a clock in the room or the 

 pressure of a pipe between the teeth while these lines are being 

 written or read. We may imagine that as the stream of conscious- 

 ness flows on, different portions come to the surface at different 

 times and under different conditions, while others fall below, often 

 to such a depth that they pass altogether beyond the margin of con- 

 sciousness. 



To speak of a " stream of consciousness " is in one sense correct ; 

 but at any moment there are probably innumerable streams, which, 

 under normal circumstances, play the part of a single or unitary 

 stream, owing to that integrative activity which we term the Ego. 

 These various streams at any moment form a pattern, but that 

 pattern is ceaselessly changing, as the streams run hither and thither. 



On the physiological side, we see the analogue of these streams 

 in the streams of nervous impulses which are perpetually coursing 

 through the brain. The pattern of these streams is likewise always 

 changing. And we may suppose that some patterns are incom- 

 patible with the simultaneous occurrence of certain other patterns. 

 In this way, we may form a physiological conception of the basis of 

 inhibition; the pattern which inhibits and that which is inhibited 

 cannot coexist. This incompatibility has doubtless been developed 



