known to like, and, since the Vital Principle recognises all things, they constitute it out of all first causes. But such as admit of only one cause and one element, set down Vital Principle as being that one, be it fire or air ; and such as admit of several first causes, set down Vital Principle as being multiple also. Anaxagoras stands alone in maintaining that mind is impassive and without anything in common with aught else ; but, even were it so, he has not explained, nor is it easy from what he has said to explain, how or for what purpose it is to recognise anything. So many writers as admit contraries among first causes, constitute the Vital Principle out of contraries, and so many as admit only one contrary, whether hot or cold, or other analogous contrast, make the Vital Principle to be that one. Hence, led by the terms, some maintain that Vital Principle is heat, because from heat the term life has been adopted; and others affirm that it is cold, because from cold, through respiration, the term Vital Principle has been derived.
Such, then, the opinions which have been transmitted to us upon Vital Principle, and such the reasons upon which those opinions have been grounded.