Motion admits of no definition, from being but a local casuality of
transitory endurance; motion is the same in all things, from an atom to
a planet, against which all difference in velocity and direction makes
no exception.
Impulsive pressure is the only cause analogous to the mechanical
effect motion; pressure is universal because matter is inert.
Motion is not natural to _inert_ matter: the term is expressive of the
local condition of a body, while the body is prevented remaining where
it is, and while the body is being passed through contiguous portions
of space.