SENSATION 



with energy. In the chemical analysis of organisms we 

 do not find any elements that are not found in inorganic 

 nature; we find that the movements in organisms obey 

 the same laws of mechanics as the latter ; we believe that 

 the conversion of energy in the living matter occurs in 

 the same way, and is provoked by the same stimuli, as 

 in inorganic matter. We are forced to conclude from 

 these experiences that the perception of stimuli — sensa- 

 tion in the objective and feeling in the subjective sense — 

 is also generally present in the two. All bodies are in a 

 certain sense "sensitive." It is just in this dynamic 

 conception of substance that monism differs essentially 

 from the materialistic system, which regards one part 

 of matter as "dead" and insensitive. In this we have 

 the best means of joining consistent materialism or 

 realism with consistent spiritualism or idealism. But, 

 as a first condition of such a tmion, we must demand 

 a recognition that organic life is subject to the same 

 general laws as inorganic nature. In both cases the 

 outer world acts alike as a stimulus on the inner world 

 of the body. We can easily see this if we glance at the 

 various kinds of sensation which correspond to the 

 various kinds of stimuli. Light and heat, external and 

 internal chemical stimuli, pressure and electricity, cause 

 analogous sensations and modifications in their effect on 

 organic and inorganic bodies. 



The effect which the light - stimulus has 'on living 

 matter, the sensation of light that results, and the 

 chemical changes of energy that follow, are of great 

 physiological importance in all organisms. We might 

 even say that sunlight is the first, oldest, and chief 

 source of organic life ; all other exertions of force depend 

 in the long run on the radiant energy of stmlight. The 

 oldest and most important function of plasm — one which 

 is at the same time a cause of its formation — is carbon- 

 assimilation ; and this plasmodomism is directly de- 



297 



