of motion their presence excites in us. In consequence, we discover in
them, extent, mobility, divisibility, solidity, gravity, and inert
force. From these general and primitive properties flow a number of
others, such as density, figure, colour, ponderosity, &c. Thus,
relatively to us, matter is all that affects our senses in any manner
whatever; the various properties we attribute to matter, by which we
discriminate its diversity, are founded on the different impressions we
receive on the changes they produce in us.

A satisfactory definition of matter has not yet been given. Man,
deceived and led astray by his prejudices, formed but vague,
superficial, and imperfect notions concerning it. He looked upon it as
an unique being, gross and passive, incapable of either moving by
itself, of forming combinations, or of producing any thing by its own
energies. Instead of this unintelligible jargon, he ought to have
contemplated it as a _genus_ of beings, of which the individuals,
although they might possess some common properties, such as extent,
divisibility, figure, &c. should not, however, be all ranked in the same
class, nor comprised under the same general denomination.

An example will serve more fully to explain what we have asserted, throw
its correctness into light, and facilitate the application. The
properties common to all matter, are extent, divisibility,
impenetrability, figure, mobility, or the property of being moved in
mass. FIRE, beside these general properties, common to all matter,
enjoys also the peculiar property of being put into activity by a motion
that produces on our organs of feeling the sensation of heat; and by
another, that communicates to our visual organs the sensation of light.
Iron, in common with matter in general, has extent and figure; is
divisible, and moveable in mass: if fire be combined with it in a