PREFACE. 



To publish a work entirely speculative, appears 

 to be a great innovation upon the fashion of philosophising, 

 which prevails in these times. To those who take the present 

 fashion for a model, or who cannot conceive any other mode 

 of inquiring into physical subjects than by experiment, an 

 abstract or speculative work must appear at least imperti- 

 nent, if not absurd, or monstrous. Notwithstanding the 

 severity of these charges, I have ventured to write, and to 

 print such a book/ not with the design of altering the present 

 fashion, or of introducing a new one ; but rather with the view 

 of furnishing materials to the experimentalists, and of offering 

 some additional suggestions, on a neglected department of 

 inquiry, upon which their labours might be bestowed with 

 apparent advantage. 



To state more precisely the design of this volume, it is to 

 trace, as far as may be done without the aid of new facts, the 

 share which those properties have in the operations and phe- 

 nomena of animal bodies, which are the causes of the distinc- 

 tion between the living and the dead states. With this view, 

 the influence of these properties is spoken of in the principal 

 relations in which it is liable to be exerted or to be considered. 

 The influence of these properties will form a distinct subject 

 of investigation in every process in which it is engaged. Such 

 distinct investigation refers to a complete development of a 

 single topic, or of any separate branch of the subject; and in 

 this respect differs from my present design, which aspires to 



