from each other only by their various modifications. Among the
individuals of the same species that come under our notice, no two
resemble exactly; and it is therefore evident that the difference of
situation alone will, necessarily, carry a diversity more or less
sensible, not only in the modifications, but also in the essence, in the
properties, in the entire system of beings. This truth was well
understood by the profound and subtle LEIBNITZ.

If this principle be properly digested, and experience seems always to
produce evidence of its truth, we must be convinced that the matter or
primitive elements which enter into the composition of bodies, are not
of the same nature, and consequently, can neither have the same
properties, nor the same modifications; and if so, they cannot have the
same mode of moving and acting. Their activity or motion, already
different, can be diversified to infinity, augmented or diminished,
accelerated or retarded, according to the combinations, the proportions,
the pressure, the density, the volume of the matter, that enters their
composition. The endless variety to be produced, will need no further
illustration than the commonest book of arithmetic furnishes us, where
it will be found, that to ring all the changes that can be produced on
twelve bells only, would occupy a space of more than ninety-one years.
The element of fire is visibly more active and more inconstant than that
of earth. This is more solid and ponderous than fire, air, or water.
According to the quantity of these elements, which enter the composition
of bodies, these must act diversely, and their motion must in some
measure partake the motion peculiar to each of their constituent parts.
Elementary fire appears to be in Nature the principle of activity; it
may be compared to a fruitful leaven, that puts the mass into
fermentation and gives it life. Earth appears to be the principle of
solidity in bodies, from its impenetrability, and by the firm coherence