To his very dear Friend, DOCTOR ARGENT, 

 the excellent and accomplished President 

 of the Royal College of Physicians, and to 

 other learned Physicians, his most esteemed 

 Colleagues. 



I have already and repeatedly presented you, my 

 learned friends, with my new views of the motion 

 and function of the heart, in my anatomical lectures ; 

 but having now for nine years and more confirmed 

 these views by multiplied demonstrations in your 

 presence, illustrated them by arguments, and freed 

 them from the objections of the most learned and 

 skilful anatomists, I at length yield to the requests, 

 I might say entreaties, of many, and here present 

 them for general consideration in this treatise. 



Were not the work indeed presented through you, 

 my learned friends, I should scarce hope that it could 

 come out scatheless and complete ; for you have in 

 general been the faithful witnesses of almost all the 

 instances from which I have either collected the truth 

 or confuted error ; you have seen my dissections, 

 and at my demonstrations of all that I maintain to 

 be objects of sense, you have been accustomed to 



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