LECTURE I. Jj' 



The term theory, in philosophical lan- 

 guage, like hypothesis, denotes the most 

 plausible and rational mode of accounting 

 for certain ph^enomena, the causes of which 

 have not been fully developed. In apply- 

 ing these terms to medical and physiologi- 

 cal subjects, I may be allowed to define 

 what I think they designate, and what I 

 intend to convey by them. By the word 

 theory I mean a rational explanation of the 

 cause or connexion of an apparently full or 

 sufficient series of facts : by hypothesis, a 

 rational conjecture concerning subjects in 

 which the series of facts is obviously incom- 

 plete. 



The formation of an hypothesis excites 

 us to enquiries, which may either confirm 

 or confute our conjectures ; and which may, 

 by enabling us to discover the deficient 

 facts, convert our hypothesis into a theory. 

 Believing the facts collected by the ingenuity 

 and industry of Mr. Hunter, to be sufficient 

 to establish his opinions respecting life, I 

 have therefore called them a theory. 



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