14 THE HARMONIES OF NATURE. 



The immense variety of colours with which the face of 

 Nature is adorned, not only affords the fullest gratification 

 to our sense of the beautiful, it is even essential to our very 

 existence, and to that of most of the higher animals ; for how 

 should we be able to find our food, or to escape from our 

 enemies, if all objects were uniformly black or white? Plunged 

 in a colourless world, man could never have become a civilised 

 being ; his fancy, his knowledge would have been crippled, his 

 mind torpid and inert. Thus there is an intimate harmony 

 between the coloured sunbeam and the wants of our spiritual 

 nature, evidently proving that both proceed from the same 

 divine source. 



The successful investigation of the properties of light is one 

 of the proudest triumphs of human ingenuity. Light darts 

 through space with an utterly inconceivable rapidity, yet man 

 has been able to measure its speed. He knows that it undulates 

 at the rate of 192,000 miles a second, and that as no less than 

 39,000 waves of red light and 57,500 waves of violet light placed 

 end to end would be required to make up an inch, the vibrations 

 of the former within that minute space of time amount to the 

 truly astounding number of 474, and those of the latter to 

 699, millions of millions ! 



In passing through various media, or on striking their surfaces, 

 light is refracted or thrown back in angles of every dimension ; 

 yet man reduces all these deviations to fixed laws, and calculates 

 them with mathematical precision. He knows whether light 

 proceeds from a self-luminous star, or whether it is only reflected 

 by a planet and thus obtains a measure for the various natures 

 of the celestial bodies. 



To be able to make all these discoveries and observations, to 

 be able to track light to inconceivable distances, or to penetrate 

 by its means into the secrets of the microscopical world, be has 

 armed his limited eyesight with truly magical instruments, which 

 reveal to him both the existence of distant worlds and that of 

 creatures so minute that many thousands find room for their 

 activity in a single drop of water ! Within the last few years he 

 has even forced light to do him service as a painter, and to trace 

 portraits or landscapes with a delicacy and perfection of touch 

 such as the human hand would vainly strive to emulate. 



What is heat ? what is light ? These questions, so difficult to 



