130. Is it then a case of _joint_-effect? Do the outer and inner substances combine, like mechanical forces, to produce the psychical result? Against such a supposition a follower of Locke would find not only the language of his master, with whom perception appears _indifferently_ as the result of the outer or inner cause, but the inherent impossibility of analysing the effect into separate elements. The ‘Law of Parsimony,’ then, will dictate to him that one or other of the causes must be dispensed with; nor, so long as he takes Locke’s identification of the outward with the real for granted, will he have much doubt as to which of the two must go. To get rid of the causality of mind, however, though it might not be untrue to the tendency of Locke, would be to lose sight of his essential merit as a formulator of what everyone thinks, which is that, at whatever cost of confusion or contradiction, he at least formulates it fully. In him the ‘Dialectic,’ which popular belief implicitly involves, goes on under our eyes. If the primacy of self-conscious thought is never recognized, if it remains the victim of its own misunderstood creations, there is at least no attempt to disguise the unrest which attaches to it in this self-imposed subjection. The mind, which Locke opposes to matter, perpetually shifting. 131. We have already noticed how the inner ‘tablet,’ on which the outer thing is supposed to act, is with Locke perpetually receding. [1] It is first the brain, to which the ‘motion of the outward parts’ must be continued in order to constitute sensation (Book II. chap. ix. sec. 3). Then perception is distinguished from sensation, and the brain itself, as the subject of sensation, becomes the outward in contrast with the understanding as the subject of perception. [2] Then perception, from being simply a reception, is converted into an ‘operation,’ and thus into an efficient of ideas. The ‘understanding’ itself, as perceptive, is now the outward which makes on the ‘mind,’ as the inner ‘tablet,’ that impression of its own operation in perception which is called an idea of reflection. [3] Nor does the regressive process--the process of finding a mind within the mind--stop here, though the distinction of inner and outer is not any further so explicitly employed in it. From mind, as receptive of, and operative about, ideas, _i.e._ consciousness, is distinguished mind as the ‘substance within us’ of which consciousness is an ‘operation’ that it sometimes exercises, sometimes (_e.g._ when it sleeps) does not (Book II. chap. i. secs. 10-12); and from this thinking substance again is distinguished the man who ‘finds it in himself and carries it about with him in a coach or on horseback (Book II. chap, xxiii. sec. 20)--the person, ‘consisting of soul and body,’ who is prone to sleep and in sound sleep is unconscious, but whose personal identity strangely consists in sameness of consciousness, sameness of an occasional operation of part of himself. [3]