WILLIAM G. STEVENSON. 61 
nomena until analysis has furnished all the facts which 
pertain to the ‘‘ physics of the brain’’; and since the 
spirit of modern science seeks only truth, regarding all 
theories and hypotheses merely as provisional instru- 
ments to this end—to be discarded for better ones when- 
ever a newly-discovered fact shall indicate the need of 
change—it is important to examine from time to time 
the record of verified facts, that we may more justly esti- 
mate the value of any theory pertaining either to matter 
or to mind, 
In the study of the brain, anatomy has revealed its 
complicated structure, and traced its development 
through many forms of life upward to man ; physiology 
and pathology have studied the wondrous functions of 
its various parts, and witnessed the psychological 
changes which follow its growth and decay ; chemistry 
has largely solved the riddle of its elements, and given 
us the agents which, without altering the most delicate 
nerve-substance, fix it in all its natural relations and so 
fit it for detailed examination ; while the microscope— 
peering into the secrets of its cell formations—has re- 
vealed myriads of elements unknown to the investigators 
of the past, and caught a shadowy outline of its mole- 
cular activities. 
From the data thus furnished comes the conviction 
that mental phenomena ‘‘are dependent upon the prop- 
erties and molecular activities of nerve-tissue’’; and 
that there isa ‘‘bond of union’’ between psychical ex- 
pressions and a nervous mechanism, although the nature 
of this union is unknown. The facts of consciousness 
are marshaled before us with all the force of attested 
verities, but are yet veiled with all the mystery of a pass- 
ing dream. 
If, then, neither science nor philosophy has fully 
classified mental phenomena as observed in the general 
average of mankind, how vain will be the attempt to 
