As this treatise may interest some who have never considered the subject for the elucidation of which it was composed, it will be well to offer a summary of that which Aristotle had undertaken to delineate, and to give, at the same time, an epitome of the opinions which, in modern times, have been entertained concerning it.
It is then that principle, which, inherent in genial matter, establishes functions distinctive of animated beings; and those functions are nutrition, and, through nutrition, growth or development, within a certain prescribed range, and absorption or rather change wrought by absorption, that is, decay. These two functions constitute, in fact, animated beings, and distinguish them broadly from whatever is inanimate; and as those functions are inherent in the simplest
