ae 
538 The Relations of Mind and Matter. [June, 
chemical phase of evolution internal energy is in the ascendant 
and controls the results. In the functional phase chemical energy 
merely holds its own, and a fixed molecular status is gained. 
But external energy acts upon tissue as a whole, and produces 
definite variations in form. 
If we now come to consider psychical evolution we find it still 
to be a question of the interplay of internal and external ener- 
gies. Reference here is made to its purely physical results, and 
not to its important characteristic of consciousness. In the 
growth of psychical conditions we still have to do with the exter- 
nal energies which play upon the body and force their way into it 
over the channels of the nerves. But as the body improves in 
its sensory organization, and permits the ready inflow of external 
energy, the balance between the two series of energies is broken, 
external energy becomes in excess and there is a tendency to 
break down the molecular complexity of the body to a lower 
level. Could all those inflowing energies play upon the muscles 
a fixed fall in the chemical level must succeed. As it is, however, 
these energies are checked in their inflow. The muscles are 
permitted to receive no more than they are prepared to accept. 
The remainder are restrained in their action to the cerebral gan- 
glion, where they exert an organizing influence upon some sub- 
stance whose character is as yet a problem. This is the third or 
psychical phase of organic evolution. 
The motor energies, thus drafted off into this cerebral sub- 
stance, there combine into a congeries of forces of yet unknown 
character, which we call the mind. It has two characteristics. 
The energies which constitute it are persistent. And they enter 
into new combinations which have no counterpart in external 
nature. It constitutes a new center of force which in its turn acts 
upon the body and aids in molding it. External forces are no 
longer supreme. A reservoir of internal energy has been formed 
which frequently acts in opposition to them. And one of the 
most essential characteristics of the action of this mental center 
of force is, that its activity is not exhausted upon the body. In 
fact it finds an important field of action in the external world. 
It molds nature as well as the body. In place of the organism 
_ needing to adapt itself to external conditions, it acts to adapt 
o external conditions to itself, and its own need of change is obvi- 
ated to the extent that it acts upon and remodels the world 
_ without. 
