SOURCES OF HUMAN KNOWLEDGE. 19 



CHAPTER II. 



SOURCES OF HUMAN KNOWLEDGE. 



OF all the information which we possess, a large, if not the larger 

 portion, is derived, either directly or indirectly, from our fellow-men. 

 Hence arises the distinction between original and communicated know- 

 ledge ; founded on the manner in which it is obtained. The term 

 original knowledge, strictly applies to that which was first discovered 

 by its possessor; being previously unknown to any person whatever: 

 while such knowledge as has been derived from others, but afterwards 

 verified by ourselves, may properly be called personal knowledge, 

 though it be not original. The knowledge of events, which we ac- 

 quire from others, and which, owing to their transient nature, can be 

 verified or proved only by testimony, may be distinguished as histo- 

 rical ; in contradistinction from which, the knowledge of general facts 

 may be called experimental; and the knowledge of general princi- 

 ples, obtained by reasoning or calculation, may be termed scientific. 



We may acquire a personal knowledge of scientific facts, and 

 principles, at any time, by voluntary application : but a persona), 

 knowledge of transient events, must, from its nature, be confined to 

 those who witnessed them ; though others may know them histori- 

 cally. Another distinction of knowledge, especially in regard to 

 the arts, is that of speculative and practical. Speculative knowledge 

 may be communicated, or derived, by study; but practical knowledge 

 can only be acquired by an actual performance of the process in 

 question ; whatever it may be. Personal knowledge, then, may be 

 acquired by observation or experiment ; by reasoning or by calcula- 

 tion : and that knowledge which has been verified by others, as well 

 as by ourselves, is perhaps the most certain of all. 



Communicated knowledge may be derived from monuments, 

 statues, coins, or other antiquities ; from books or manuscripts,, 

 pictures or engravings ; and from conversation, gestures, or signals, 

 in immediate intercourse with our fellow-men. Of all these sources 

 of knowledge, books and conversation are, at the present day, much 

 the most important. . Conversation may produce the liveliest impres- 

 sions upon the mind ; but those impressions, once effaced, cannot 

 always be restored : while books have the countervailing advantage, 

 that we can recur to them at pleasure, and revive the ideas which 

 they have furnished, although long lost or forgotten. In developing 

 this subject farther, we shall treat, 1. Of the Ancient Schools of 

 Philosophy ; 2. Of Modern Learned Societies ; 3. Of Libraries ; 

 and, 4. Of Encyclopedias. 



The Ancient Schools of Philosophy. 



Philosophy was formerly understood to comprehend the principles 

 of all human knowledge ; or, in the words of Cicero, " the knowledge 

 of things divine and human, and of the causes by which they am 



