of Edinburgh, Session 18G9-70. 151 
would think it a sufficient explanation to say that the man is a 
lunatic. He should remember, however, that he owes this ex¬ 
planation to the physiological method. Formerly, the explanation, 
according to the reflective method was, and with many still is, that 
the lunatic is either inspired or else possessed by a spiritual being. 
The inductive philosophy, starting from the fundamental fact that 
all states of consciousness of a man, however manifested, cannot be 
manifested independently of vital processes, lays down the law that 
in the living man Life and Mind are inseparable, and consequently 
that the “thinking Ego” is the man himself. Now, although 
bis person is double, whether as to limbs or brains, his corporeal 
condition of unity is no more affected thereby in a healthy state 
than the unity revealed in consciousness—the one being the reflex 
of the other. His two brains act together so as to attain the unity 
of consciousness, just as his two eyes act in unitj^ of vision; but 
as he may see double when the two eyes act disjointly, so may he 
have a double consciousness when the two brains act disjointly. 
Whether he believes, or whether he doubts that he sees two objects, 
or that he is one or two persons, depends upon those molecular 
conditions upon which the belief and doubt of the moment depend. 
Or, again, just as an object of vision may, from disorder of the 
corresponding brain-tissue, appear to a man to be something wholly 
different, as when his friend appears to be the devil, constituting 
what is termed a hallucination, so his personality, from disorder of 
the corresponding brain-tissue, may appear to be something wholly 
different, and he may chance to have an hallucination that he is 
the devil. It appears probable, therefore, that although a man may 
have many and various delusions as to his state of mind and body, 
he will rarely exceed three distinct and fixed delusions as to his 
personality, viz., one resulting from disorder of each brain acting 
disjointly, and one from disorder of both acting conjointly. Under 
the restrictions stated, the result of numerous observations I have 
made is in accordance with this view. So much for the break-up 
of the unity of consciousness by brain disorder. It is obvious at a 
glance that these diversities of belief as to personal identity are 
associated with brain changes involving memory and reminiscence; 
otherwise, when Elliot came to a belief in his royal birth and 
parentage, he would also remember, to the confusion of the belief, 
