CHAPTER XII. 



MENTAL FUNCTION. 



ANOTHER of the various modes of activity which are in one way or 

 another directly connected with the human organism is consciousness, or 

 mind. Reduced to its very simplest biological terms, this is the feeling of 

 being alive. It is necessary to discuss this aspect of the individual for 

 several reasons, the most important of which perhaps is the fact, obvious 

 but often ignored, that every person is not merely a body but also a mind, 

 neither being complete or easily thinkable without the other. It is one of 

 the greatest defects in the practice of the scientific medical art that many 

 far too often disregard the mental aspect of the individual. Indeed, 

 only in very recent years has the medical profession as a whole begun to 

 realize the importance of this mental "half" of his patients. These two 

 aspects practically inter-act in almost every phase, and the mind is 

 scarcely more dependent on the body than is the body on the mind. In 

 no sense, however, is the mental process a function of the body but rather 

 in reality the body is only the material instrument of the mind. We have 

 no intention of entering for a moment upon any metaphysical discussion 

 of the relations of body and mind. It is only necessary here to assume 

 the common theory that these "two" probably are different aspects of 

 one reality. If we take Fechner's famous simile of the arc of a circle, 

 the bodily events are like the outer aspect of this curve and the mental 

 process the same line as seen from the inside. Consciousness, properly 

 speaking, cannot be defined. Its only definition consists in living it, 

 and yet we may say that in a narrow sense the mental process is the 

 experience that an animal has of its external and internal environment. 



Consciousness is inherently a process, and psychology no longer pur- 

 sues i-ts ancient search after a substantial soul. The soul for modern 

 thought is an ethical thing and psychologically that which James has 

 made known the world over as the stream of consciousness. In the 

 following brief description of the mental functions all that we wish to 

 examine is facts, the "what" without the "how" and usually without 

 the "why." We desire only a simple, straight-forward description of 

 the outlines of the human mental process in those aspects most closely 

 connected with the organism. This is properly a part of physiology, 

 not only because from any and every point of view mind is connected 

 undeniably with organic function, but because the physician and the 

 student need to know much better than they often do the other side of 

 man's nature, about his "fire" as well as about the structure of his 

 "clay." The time has nearly come when the scientific physiologist 



