ion of the vessel, of the waves, and of the earth.
The common view of motion as an activity is erroneous; since it requires
force not only to set in motion bodies which are at rest, but also to stop
those which are in motion, it is clear that motion implies no more activity
than rest. Both are simply different states of matter. Since there is no
empty space, each motion spreads to a whole circle of bodies: A forces B
out of its place, B drives out C, and so on, until Z takes up the position
which A has left.

The ultimate cause of motion is God. He has created bodies with an
original measure of motion and rest, and, in accordance with his immutable
character, he preserves this quantity of motion unchanged: it remains
constant in the world as a whole, though it varies in individual bodies.
For with the power to create or destroy motion bodies lack, further, the
power to alter their quantity of motion. By the side of God, the primary
cause of motion, the laws of motion appear as secondary causes. The first
of these is the one become familiar under the name, law of inertia:
Everything continues of itself in the state (of motion or rest) in which it
is, and changes its state only as a result of some extraneous cause. The
second of these laws, which are so valuable in mechanics, runs: Every
portion of matter tends to continue a motion which has been begun in the
same direction, hence in a straight line, and changes its direction only
under the influence of another body, as in the case of the circle above
described. Descartes bases these laws on the unchangeableness of God and
the simplicity of his world-conserving (_i.e._, constantly creative)
activity. The third law relates to the communication of motion; but
Descartes does not recognize the equality of action and reaction as
universally as the fact demands. If a body in motion meets another body,
and its power (to continue its motion in a straight line) is less than the
resistance of the other on which it has impinged, it retains its motion,
but in a different direction: it rebounds in the opposite direction. If, on
the contrary, its force is greater, it carries the other body along with
it, and loses so much of its own motion as it imparts to the latter. The
seven further rules added to these contain much that is erroneous. As
_actio in distans_ is rejected, all the phenomena of motion are traced back
to pressure and impulse. The distinction between fluid and solid bodies i