72 FRAGMENTS OF SCIENCE. 



The outward facts of nature are insufficient to satisfy 

 the mind. We cannot be content with knowing that 

 the light and heat of the sun illuminate and warm the 

 world. We are led irresistibly to enquire, ' What is 

 light, and what is heat ? ' and this question leads us at 

 once out of the region of sense into that of imagination. 1 

 Thus pondering, and questioning, and striving to 

 supplement that which is felt and seen, but which is 

 incomplete, by something unfelt and unseen which is 

 necessary to its completeness, men of genius have in 

 part discerned, not only the nature of ligfyt and heat, 

 but also, through them, the general relationship of 

 natural phenomena. The working power of Nature 

 consists of actual or potential motion, of which all 

 its phenomena are but special forms. This motion 

 manifests itself in tangible and in intangible matter, 

 being incessantly transferred from the one to the other, 

 and incessantly transformed by the change. It is as 

 real in the waves of the aether as in the waves of the 

 sea ; the latter derived as they are from winds, which 

 in their turn are derived from the sun are, indeed, 

 nothing more than the heaped-up motion of the aether 

 waves. It is the calorific waves emitted by the sun 

 which heat our air, produce our winds, and hence 

 agitate our ocean. . And whether they break in foam 

 upon the shore, or rub silently against the ocean's bed, 

 or subside by the mutual friction of their own parts, 

 the sea waves, which cannot subside without producing 

 heat, finally resolve themselves into waves of aether, 

 thus regenerating the motion from which their tempo- 

 rary existence was derived. This connection is typical. 

 Nature is not an aggregate of independent parts, but 

 an organic whole. If you open a piano and sing into 



1 This line of thought was pursued farther five years subse- 

 quently. See * Scientific Use of the Imagination ' in Vol. II. 



