142 MYTH AND SCIENCE. 



so-called abstract ideas, although it is sometimes 

 asserted that they are purely spiritual and intellectual 

 acts, remote from every physiological process of fact 

 and sense. An actual physiological fact (colour in 

 this instance) corresponds to the idea in the nervous 

 centres, and reproduces the sensation due to the per- 

 ception of special ohjects, whose physical quality of 

 whiteness we have perceived, and this sensation makes 

 part of the abstract, or rather indefinite conception. 



In fact, all which is not actually present to the 

 mind and the present is an infinitesimal fraction 

 of knowledge is reproduced by the memory, and 

 this is effected by the molecular movements of the 

 human brain, and by what may be called the ethereal 

 modifications which took place when the sensations, 

 perceptions, and acts first occurred. If the cells 

 vibrate, and the organs of the brain are affected by 

 the recollection of past ideas and acts, just as when 

 they actually occurred (and this appears from Schiff s 

 experiences as to the increase of the brain in heat 

 and volume during dreams), this vibration will be 

 still more marked when any quality which affects 

 our senses is reproduced in the mind. 



The particular form of the quality as it appears in 

 a definite object is certainly wanting in the abstract 

 conception ; it remains in the first stage of pure 

 sensation, like a spontaneous act of observation, and 

 it is transformed into apprehension by the mental 

 faculty. But the inward consciousness of the quality 



