Again, we notice that the whole collection of living things in any one 

 place is constantly changing. Has each kind always existed as we see it 

 now? What of the kinds that formerly lived here? How did the indi- 

 viduals originate ? Even if we begin with the practical questions of getting 

 what we need and avoiding injury, many other questions are bound to 

 arise. What conditions favor living or interfere with it ? How do different 

 kinds of living things influence one another? Each of these questions may 

 start us off on a new study or special "science of life", of which there 

 are many. 



The answers we get to such questions make us act differently in connec- 

 tion with various plants and animals, including other people. But what we 

 do changes the conditions around us — and raises new problems. 



So we have to learn about living beings, including ourselves, whether we 

 like biology or not. And everybody is doing it. For biology is that branch 

 of science which has to do especially with life processes. This knowledge 

 helps us to preserve and improve our own lives. 



