iscourse of Natural Philosophy, we judge
it necessary, in the first place and chiefly, to divide the body of
philosophy into its proper members, so that we may know what is that
which is called philosophy, and what part of it is physical, or the
explanation of natural things. The Stoics affirm that wisdom is the
knowledge of things human and divine; that philosophy is the pursuit of
that art which is convenient to this knowledge; that virtue is the sole
and sovereign art which is thus convenient; and this distributes itself
into three general parts--natural, moral, and logical. By which just
reason (they say) philosophy is tripartite; of which one natural, the
other moral, the third logical. The natural when our inquiries are
concerning the world and all things contained in it; the ethical is the
employment of our minds in those things which concern the manners of
man's life; the logical (which they also call dialectical) regulates our
conversation with others in speaking. Aristotle, Theophrastus, and after
them almost all the Peripatetics give the same division of philosophy.
It is absolutely requisite that the complete person he contemplator of
things which have a being, and the practiser of those thing which are
decent; and this easily appears by the following instances. If the
question be proposed, whether the sun, which is so conspicuous to us, be
informed of a soul or inanimate, he that makes this disquisition is the
thinking man; for he proceeds no farther than to consider the nature of
that thing which is proposed. Likewise, if the question be propounded,
whether the world be infinite, or whether beyond the system of this
world there is any real being, all these things are the objects about
which the understanding of man is conversant.

But if these be the questions,--what measures must be taken to compose
the well-ordered life of man, what are the best methods to govern and
educate children, or what are the exact rules whereby sovereigns may
command and establish laws,--all these queries are proposed for the sole
end of action, and the man skilled therein is the moral and practical
man.

CHAPTER I. WHAT IS NATURE?

Since we have undertaken to make a diligent search into Nature, I cannot
but conclude it necessary to declare what Nature is. It is very absurd
to attempt a discourse of the essence of natural things, and not to
understand what is the power and sphere of Nature. If Aristotle be
credited, Natur