14 LEARNING FROM THE BOOK. 



US with only a very limited portion of that which it 

 is necessary for us to know. This is the case upon 

 all subjects, but it is more especially the case in 

 natural history, where, before we can rightly under- 

 stand one part, we must have a knowledge of so 

 many. The productions of nature depend so much 

 on local causes, that those which can be seen even by 

 the most active and adventurous traveller, amount 

 only to a very small fraction of the w-hole. Hence 

 we must, with reference to by far the greater majority 

 of subjects, have recourse to information at second 

 hand, and this may be regarded as the second general 

 means of obtaining knowledge. 



Now, on most subjects generally, and on many 

 subjects exclusively, the best mode of obtaining this 

 secondliand information, is through the medium of 

 books ; because these are accessible at all times ; and 

 therefore those persons, who are the most actively 

 employed, may, if so inclined, acquire, by means of 

 books, a great quantity — nay, almost any quantity of 

 knowledge, and that during portions of time which 

 are individually so short that, if not occupied in this 

 manner, they are very apt to be utterly lost. There 

 is another advantage which books possess, even over 

 direct personal observation : we live at a point of 

 the earth's surface, as it were, and our direct obser- 

 vation is limited to a small distance round that 

 point, so that our observation is confined to a certain 

 class of objects, dependent on locality and latitude in 

 so far as they are natural ; and these are very often 

 not the ones that it is most desirable or most useful 

 to know, and they themselves cannot be understood 

 in a satisfactory manner without the knowledge not 

 only of other things which He without the sphere of 



