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Physics
By Aristotle
Translated by R. P. Hardie and R. K. Gaye
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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.
The principles in question must be either (a) one or (b) more than
one. If (a) one, it must be either (i) motionless, as Parmenides and
Melissus assert, or (ii) in motion, as the physicists hold, some declaring
air to be the first principle, others water. If (b) more than one,
then either (i) a finite or (ii) an infinite plurality. If (i) finite
(but more than one), then either two or three or four or some other
number. If (ii) infinite, then either as Democritus believed one in
kind, but differing in shape or form; or different in kind and even
contrary.
A similar inquiry is made by those who inquire into the number of
existents: for they inquire whether the ultimate constituents of existing
things are one or many, and if many, whether a finite or an infinite
plurality. So they too are inquiring whether the principle or element
is one or many.