s? Whence proceed laws so ingenious, so just,
so well adapted one to the other, that the least alteration of or
deviation from which would, on a sudden, overturn and destroy all
the excellent order we admire in the universe? A body being
entirely distinct from another, is in its nature absolutely
independent from it in all respects. Whence it follows that it
should not receive anything from it, or be susceptible of any of its
impressions. The modifications of a body imply no necessary reason
to modify in the same manner another body, whose being is entirely
independent from the being of the first. It is to no purpose to
allege that the most solid and most heavy bodies carry or force away
those that are less big and less solid; and that, according to this
rule, a great leaden ball ought to move a great ball of ivory. We
do not speak of the fact; we only inquire into the cause of it. The
fact is certain, and therefore the cause ought likewise to be
certain and precise. Let us look for it without any manner of
prepossession or prejudice. What is the reason that a great body
carries off a little one? The thing might as naturally happen quite
otherwise; for it might as well happen that the most solid body
should never move any other body--that is to say, motion might be
incommunicable. Nothing but custom obliges us to suppose that
Nature ought to act as it does.

SECT. LXXXI. To give a satisfactory Account of Motion we must
recur to the First Mover.

Moreover, it has been proved that matter cannot be either infinite
or eternal; and, therefore, there must be supposed both a first atom
(by which motion must have begun at a precise moment), and a first
concourse of atoms (that must have formed the first combination).
Now, I ask what mover gave motion to that first atom, and first set
the great machine of the universe a-going? It is not possible to
elude this home question by an endless circle, for this question,
lying within a finite circumference, must have an end at last; and
so we must find the first atom in motion, and the first moment of
that first motion, together with the first mover, whose hand made
that first impression.

SECT. LXXXII. No Law of Motion has its Foundation in the Essence
of the Body; and most of those Laws are Arbitrary.

Among the laws of motion we must look upon all those as arbitrary
which we cannot account for by the very essence of bodies. We have
already made out that