AND ANIMAL LIFE. 381 



cept on the supposed existence of a peculiar 

 vital principle, whose attributes are like those 

 of a spirit possessing an unembodied form, sensa- 

 tion, and perception, which is continually on the 

 look out, in order to protect the body from 

 insidious attacks or dangerous breaches, but, 

 when it finds itself unequal to the contest, 

 retires and allows the assailant to devastate the 

 domains it so lately governed and beautified. 

 Having proceeded thus far in the investigation 

 of the nature of the vital principle, I shall en- 

 deavour, in the next section, to make still closer 

 approximations to a knowledge of that vivify- 

 ing principle, by means of which the organic 

 functions and the animal (of course considering 

 the immortal mind as a separate existence) are 

 maintained in the exercise of their various 

 powers. 



SECT. II. An Inquiry into the Nature of that Principle 

 by means of which the System is maintained in Health 

 and Vigour. 



CCCCLIV. THAT the principle of life is 

 ject to an increase and diminution, must appear 

 probable to the most superficial observer of Na- 

 ture ; but, if he investigate the subject profound- 

 ly, his doubts and probabilities will perhaps be 

 exchanged for certainties. In marking the exu- 



