all in the true or absolute, which should therefore be alone regarded in
philosophy. And the true as we are told are distinguished from apparent
or relative motions by the following properties.--First, in true or
absolute motion all parts which preserve the same position with respect
of the whole, partake of the motions of the whole. Secondly, the place
being moved, that which is placed therein is also moved; so that a body
moving in a place which is in motion doth participate the motion of its
place. Thirdly, true motion is never generated or changed otherwise than
by force impressed on the body itself. Fourthly, true motion is always
changed by force impressed on the body moved. Fifthly, in circular motion
barely relative there is no centrifugal force, which, nevertheless, in
that which is true or absolute, is proportional to the quantity of
motion.

112. MOTION, WHETHER REAL OR APPARENT, RELATIVE.--But, notwithstanding
what has been said, I must confess it does not appear to me that
there can be any motion other than relative; so that to conceive
motion there must be at least conceived two bodies, whereof the
distance or position in regard to each other is varied. Hence, if there
was one only body in being it could not possibly be moved. This seems
evident, in that the idea I have of motion doth necessarily include
relation.

113. APPARENT MOTION DENIED.--But, though in every motion it be
necessary to conceive more bodies than one, yet it may be that one
only is moved, namely, that on which the force causing the change
in the distance or situation of the bodies, is impressed. For, however
some may define relative motion, so as to term that body moved
which changes its distance from some other body, whether the force
or action causing that change were impressed on it or no, yet as