4 ANALYTIC SECT. I. 
years received the support of several physiologists 
of great repute. But supposing their identity 
completely established, which I conceive is the 
case; physiological research is not therefore to 
remain stationary. Our knowledge even of 
galvanism is confined to a few of its properties, 
its nature being quite unknown; nor, indeed, is 
the knowledge of first causes absolutely requisite 
for practical utility. The chemist estimates the 
specific gravity of an elementary body,describes its 
colour, and determines its combinations with other . 
substances, without pretending to comprehend its 
ultimate particles. The mathematician also caleu- 
lates the force with which attraction operates 
on bodies at various distances, without holding 
himself bound to say what attraction is. Ought 
not the physiologist to follow a similar principle 
in the investigation of the animal functions, and 
leave the nature of the vital force in the same 
uncertainty as the chemist does the atoms of an 
element, and the mathematician attraction? This 
is the view of the vital force which I propose to 
take; but I shall, nevertheless, point out, as I 
proceed, its analogies to galvanic electricity. 
