certain proportion, the iron acquires two new properties; namely, those
of exciting in us similar sensations of heat and light, which were
excited by the element of fire, but which the iron had not, before its
combination with the igneous matter. These distinguishing properties are
inseparable from matter, and the phenomena that result, may, in the
strictest sense of the word, be said to result necessarily.

If we contemplate a little the paths of Nature--if, for a time, we trace
the beings in this Nature, under the different states through which, by
reason of their properties, they are compelled to pass; we shall
discover, that it is to motion, and motion only, that is to be ascribed
all the changes, all the combinations, all the forms, in short, all the
various modifications of matter. That it is by motion every thing that
exists is produced, experiences change, expands, and is destroyed. It is
motion that alters the aspect of beings; that adds to, or takes away
from their properties; which obliges each of them, by a consequence of
its nature, after having occupied a certain rank or order, to quit it,
to occupy another, and to contribute to the generation, maintenance, and
decomposition of other beings, totally different in their bulk, rank,
and essence.

In what experimental philosophers have styled the THREE ORDERS OF
NATURE, that is to say, the _mineral_, the _vegetable_, and _animal_
worlds, they have established, by the aid of motion, a transmigration,
an exchange, a continual circulation in the particles of matter. Nature
has occasion in one place, for those particles which, for a time, she
has placed in another. These particles, after having, by particular
combinations, constituted beings endued with peculiar essences, with
specific properties, with determinate modes of action, dissolve and
separate with more or less facility; and combining in a new manner, they