WHEN the objects of an inquiry, in any department, have
principles, conditions, or elements, it is through acquaintance with
these that knowledge, that is to say scientific knowledge, is
attained. For we do not think that we know a thing until we are
acquainted with its primary conditions or first principles, and have
carried our analysis as far as its simplest elements. Plainly
therefore in the science of Nature, as in other branches of study, our
first task will be to try to determine what relates to its principles.

    The natural way of doing this is to start from the things which
are more knowable and obvious to us and proceed towards those which
are clearer and more knowable by nature; for the same things are not
"knowable relatively to us" and "knowable" without qualification. So
in the present inquiry we must follow this method and advance from
what is more obscure by nature, but clearer to us, towards what is
more clear and more knowable by nature.

    Now what is to us plain and obvious at first is rather confused
masses, the elements and principles of which become known to us
later by analysis. Thus we must advance from generalities to
particulars; for it is a whole that is best known to sense-perception,
and a generality is a kind of whole, comprehending many things
within it, like parts. Much the same thing happens in the relation
of the name to the formula. A name, e.g. "round", means vaguely a sort
of whole: its definition analyses this into its particular senses.
Similarly a child begins by calling all men "father", and all women
"mother", but later on distinguishes each of them.