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LECTURE I. 23 



mation of our labours with satisfaction ; and 

 being unable to display to others the dif- 

 ferent series of facts and opinions, and 

 modes of inference, we express our cer- 

 tainty of the conclusion, by saying, it must 

 be so ; it is absurd to suppose otherwise ; 

 or, as they say Dr. Johnson was accustomed 

 to do, " I know I'm right, so there's an 

 end of it." 



Now these ultimate opinions, for so I 

 may call them, as being the last of a se- 

 ries, become primary and elementary in 

 the display of knowledge. These conclu- 

 sions of thought become principles of sci- 

 ence and of conduct. By the prosecution 

 of thought, we are led to observe the very 

 trunk and roots from which the various 

 ramifications of our knowledge are pro- 

 duced, and the nature of the ground on 

 which the whole is supported, so that we 

 become assured of its security, or admo- 

 nished of its uncertainty. It is then, to 

 certain ultimate opinions, or physiological 

 conclusions of Mr. Hunter, with respect to 

 the vital processes, that I chiefly wish, on 



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