motion is a manner of existence, that flows, necessarily, out of the
nature of matter; that matter moves by its own peculiar energies; that
its motion is to be attributed to the force which is inherent in itself;
that the variety of motion, and the phenomena which result, proceed from
the diversity of the properties--of the qualities--of the combinations,
which are originally found in the primitive matter, of which Nature is
the assemblage.

Natural philosophers, for the most part, have regarded as inanimate, or
as deprived of the faculty of motion, those bodies which are only moved
by the intervention of some agent or exterior cause; they have
considered themselves justified in concluding, that the matter which
forms these bodies is perfectly inert in its nature. They have not
forsaken this error, although they must have observed, that whenever a
body is left to itself, or disengaged from those obstructions which
oppose themselves to its descent, it has a tendency to fall or to
approach the centre of the earth, by a motion uniformly accelerated;
they have rather chosen to suppose a visionary exterior cause, of which
they themselves had but an imperfect idea, than admit that these bodies
held their motion from their own peculiar nature.

These philosophers, also, notwithstanding they saw above them an
infinite number of globes that moved with great rapidity round a common
centre, still adhered to their favourite opinions; and never ceased to
suppose some whimsical causes for these movements, until the immortal
NEWTON clearly demonstrated that it was the effect of the gravitation of
these celestial bodies towards each other. Experimental philosophers,
however, and amongst them the great Newton himself, have held the cause
of gravitation as inexplicable. Notwithstanding the great weight of this
authority, it appears manifest that it may be deduced from the motion of