. I. PHYSICO-CHEMICAL PHENOMENA. 27 



livion ; but by demonstrating that attraction is exercised in 

 the direct ratio of the masses, and in the inverse ratio of 

 the squares of the distance, and by thus unfolding the eter- 

 nal laws of this force, Newton has rendered his name im- 

 mortal. 



To speak of the vital forces, to give them a definition, to 

 interpret phenomena by their aid, and yet to be ignorant of 

 the laws which govern them, is doing nothing, or rather it 

 is doing what is worse than nothing. It is to attempt an 

 impossibility, it is to content the mind to no purpose, to stop 

 the search after truth. To state that the liver separates the 

 elements of the bile from the blood by means of the vital 

 force, is merely to assert that the bile is formed in the liver. 

 By thus varying the expression a dangerous illusion is esta- 

 blished. 



Physico-chemical Phenomena. I believe that I have clear- 

 ly shown the object we ought to aim at in studying the phe- 

 nomena of living beings, which returns in its ultimate ana- 

 lysis to the examination of the physico-chemical phenomena 

 of these bodies, of the modifications which organization 

 effects in the general action of physical agents, and, lastly, 

 to the investigation of the laws, at present empirical, of the 

 purely vital phenomena. 



I hope I have succeeded in fully determining what are 

 the limits within which we ought to confine ourselves, in 

 the vast domain of physiology, and what part of the subject 

 we ought to study under the title of the physico-chemical 

 phenomena of living beings. The generalities which I have 

 now stated must be sufficient to prove the importance of 

 understanding the functions of living beings. 



Precision of Language. In these lectures I propose to 

 myself another, and not less important, object; it is to in- 

 troduce, in the exposition of physiological facts, and in the 

 investigation of their laws, that precision of language, that 



