252 PHYSICAL EXPRESSION. 



explanation ? As the object moves, different 

 portions of the retina will be stimulated ; and the 

 greater the area of retina stimulated, the greater 

 the stimulus transmitted to the nerve-centres 

 which move the head and eyes, the greater also the 

 inhibitory or stimulating effect produced upon the 

 spontaneous movements. 



In the adult the objective criteria of mind are 

 modes of expression ; the expressions of the emotions r 

 feelings, passions, thoughts are indications of the 

 mind ; and all these modes of expression have been 

 shown to be produced by direct action of the nerve- 

 system. It is, then, admitted that conditions of 

 the mind are directly expressed by nerve-muscular 

 signs. This implies that some material, physical 

 change occurs along with "mentation," which 

 material change is expressed in the muscles of the 

 body. It is this inherent physical change, thus 

 directly expressed, which the physiologist investi- 

 gates in his studies of mind; and whether that 

 inherent nerve-change, thus directly expressed, be 

 mind itself, or in some way allied to mind, is a 

 metaphysical question I shall not attempt to discuss. 

 Here we only discuss material, physical action. 



Let us take an example or two. A mother just 

 after the loss of her infant comes to speak of its 

 death. We then see the face tending to flush, the 

 mouth quivering, the angles depressed ; she speaks 

 with a trembling voice, half choked by her emotion, 



The term " mind " is used as the collection of all 

 the properties that make up the faculty mentation. 

 We cannot by physiological methods investigate 



