WHAT BIOLOGY TEACHES. 9 



which the world is composed, are found essentially 

 connected with living beings. Geology also shows us 

 that there were vast periods in the past history of the 

 earth when no life existed. These periods are hence 

 called azoic, or without life. At the present time, 

 the ice-fields of the poles, and the great deserts, are to 

 a large extent lifeless. It is plain, therefore, that life 

 is not an essential part of creation. Suns and planets 

 would shine ; gravity, light, heat, and electricity 

 would operate ; and chemical changes take place, if 

 there were no living beings. From this consideration 

 we see clearly that Biology embraces something more 

 than the study of the laws and phenomena of non- 

 living matter. It is the science of life. It concerns 

 itself with every thing pertaining to life. 



5. The question, What is life ? has given rise to vari- 

 ous speculations in every age of history to the present 

 day. Some of the Greek philosophers taught that 

 it was the result of the harmony or agreement of the 

 different parts of the body ; and this view is repeated 

 in modern times by those who claim that life is the 

 result of organization. It requires but little thought 

 to see that this is no explanation at all. Since all 

 organization depends on living matter, as we shall 

 more fully perceive hereafter, one might as wisely 

 say that an architect or carpenter was the result of a 

 house, as to say that life results from organization. 



Some have claimed that life is a sort of refined 



