252 LIGHT. 



run of several thousand miles. So that those minor 

 operations of these internal fires of the earth are 

 necessary to account for the inequalities of the sur- 

 face, which are not formed of rock but of accumu- 

 lated fragments. 



They also enable us to account for the formation 

 of beds of chalk, and shelly limestone, and marble 

 in all their varieties of form. 



?' " " 



SECTION VIII. 



Observation of organized Beings. 



IN the former sections, an attempt has been made 

 to call the attention of the reader to the objects and 

 phenomena of the creation around him, in their gen- 

 eral appearances and properties as matter, and with- 

 out any reference to the particular forms of individ- 

 ual subjects. 



Light is nearly the same wherever it may fall, or 

 from whatever it may be produced ; and though the 

 light which comes to us from one substance is often 

 very different, in colour and intensity, from that 

 which comes from another, the portion that does 

 come to our eyes is still a part of the same specific 

 light, which is entire and undecomposed in the beams 

 of the sun. When the fields send us back the green, 

 and, as we suppose, drink up the red, that red wholly 

 disappears in the leaves and the grass ; and, in like 

 manner, when any other colour is given out to us, 

 the remainder is absorbed, and we cannot, by any 

 scrutiny in which we can engage, find out what 

 becomes of the portion which is retained by any 

 substance, or how it affects the other properties of 

 that substance. 



As we can, by means of the prism, decompose the 



