THE STRUGGLE FOR REALITIES. 369 
his entrances.” He is a rare man who can add a new 
meaning to his lines or give a better cue to him that 
follows. 
The nervous system of man and animals is primarily 
a device for making locomotion safe. The mind—using 
the word in the broadest sense—is a col- 
lective term for the operations of the 
nervous system. It is not an entity ex- 
isting apart from organization. To it consciousness is 
related much as the flame is to fire. The mind is in 
operation whether we realize it or not. The reflex ac- 
tion of the nerve centre is the type of all mind pro- 
cesses. Through the sensory nerves, impressions of the 
external world are received by the brain or central gan- 
glion. The brain has no source of knowledge other 
than through sensation. All human knowledge comes 
through human experience. The primal function of the 
brain, sitting in darkness, is to convert sensory impres- 
sions into impulses of action. To this end are devel- 
oped the motor nerves which pass from the nerve cen- 
tre outward to the muscles. The sensory organs are 
the brain’s sole teacher; the muscles are its only serv- 
ants. The essence of the intellect, as distinguished 
from reflex. or instinctive action, is the choice among 
different motor responses to the stimulus of external 
conditions. As the conditions of life grow more com- 
plicated, the possible ways in which sensation may pass 
over into action grow more numerous. It is the func- 
tion of the intellect to consider these, and of the will to 
choose. The growth of the intellect causes and permits 
complexity of life. Safety in life depends upon choos- 
ing the right response. Wrong choice leads to failure 
and death. The power of choice implies the necessity 
of choosing right. 
"From this, by the process of natural selection, arises 
Nature of the 
mind, 
x. 
