VITAL PRINCIPLE. 23 
able us to accomplish this task. It scarcely warrants us to 
hope that the object is attainable. We know, however, 
that the following circumstances are imvariably present, 
whenever the vital principle begins to exhibit its move- 
ments. 
1. A Parent.—Previous to the independent existence of 
a plant or animal, it is necessary that they shall have form- 
ed a part of some other body similar to themselves. This 
condition is ascertained in so satisfactory a manner, in the 
case of the more perfect organized beings, as to preclude 
the possibility of a doubt. There are, however, many 
plants and animals, with whose manner of growth and 
mode of propagation, we are so imperfectly acquainted, 
that we must rely upon the evidence of analogy for the 
conclusions which we form with respect to their origin. 
But as all the living bodies whose history has been. stu- 
died with care, have evidently participated in the existence 
of other living bodies, before they exercised the functions 
of life for themselves, the presumption, that the same kind 
of generation takes place in every organized body, offers all 
the claims of a legitimate deduction. Life, then, may be 
considered as proceeding from life, as transmitted from one 
individual to another, and :as dating its actual origin from 
the period when the voice of Omnipotence uttered the 
words, * Let the Earth bring forth.” 
The ancients, whose opimions respecting the nature of 
generation were necessarily obscure, from the want of pro- 
per instruments and methods of observation, considered 
living bodies as produced in two different ways. In the 
first, exemplified in the case of the more perfect animals 
and vegetables, they considered organized bodies as pro- 
ceeding from other organized bodies, by a process which is 
termed Univocal or Regular Generation. In the second, 
they supposed that the putrefaction of different bodies, 
