Aristotle, pursuing his general reflections about Existence, says that in everything that exists you can trace three principles: the Matter out of which the thing arose, and which contained the possibility of its existence; the Form or actual nature which the thing possesses; and the Negation or Privation of all other natures. That is to say—a thing is what it is by not being what it is not. And thus all existence has a negative, as well as a positive, side ('Phys.' I. ix.) These remarks form a metaphysical basis to Natural Philosophy.
In the second book of his 'Physical Discourse,' Aristotle quits the region of pure abstractions, and states, in interesting terms, his views of "Nature." He speaks of "Nature" as "a principle of motion and rest essentially inherent in things, whether that motion be locomotion, increase, decay, or alteration." "It is absurd to try to prove the existence of Nature; its existence is self-evident." "Nature may be said in one way to be the simplest substratum of matter in things possessing their own principle of motion and change; in another way it may be called the form or law of such things." In other words. Nature is both "matter or potentiality, and form or actuality; both the simple elements of a thing and its existence in perfection. It is also the transition from the one to the other. "Nature," says Aristotle, "spoken of as the creation of anything, is the path to nature."
Paley's 'Natural Theology' opens with the celebrated argument which compares the world to a watch. "If one were to find a watch," says Paley, "he would
