ffices," The term nature, when it is at all distinguished in the Stoic
system from God, denotes not a separate agent, but that order of things
which is necessarily produced by his perpetual agency. Since the active
principle of nature is comprehended within the world, and with matter
makes one whole, it necessarily follows that God penetrates, pervades,
and animates matter, and the things which are formed from it; or, in
other words, that he is the soul of the universe.

The universe is, according to Zeno and his followers, "a sentient
and animated being." Nor was this a new tenet, but, in some sort, the
doctrine of all antiquity. Pythagoras, Heraclitus, and after these,
Zeno, taking it for granted that there is no real existence which is
not corporeal, conceived nature to be one whole, consisting of a subtle
ether and gross matter, the former the active, the latter the passive
principle, as essentially united as the soul and body of man that is,
they supposed God, with respect to nature, to be, not a co-existing, but
an informing principle.

Concerning the second principle in the universe, matter, and concerning
the visible world, the doctrine of the Stoics is briefly this:--Matter
is the first essence of all things, destitute of, but capable of
receiving, qualities. Considered universally, it is an eternal whole,
which neither increases nor decreases. Consideree! with respect to
its parts, it is capable of increase or diminution, of collision and
separation, and is perpetually changing. Bodies are continually tending
towards dissolution; matter always remains the same. Matter is not
infinite, but finite, being circumscribed by the limits of the world;
but its parts are infinitely divisible. The world is spherical in its
form; and is surrounded by an infinite vacuum. The action of the divine
nature upon matter first produced the element of moisture, and then the
other elements, fire, air, and earth, of which all bodies are composed.
Air and fire have essential levity, or tend towards the exterior surface
of the world; earth and water have essential gravity, or tend towards
the centre. All the elements are capable of reciprocal conversion; air
passing into fire, or into water; earth into air and water; but there
is this essential difference among the elements, that fire and air
have within themselves a principle of motion, while water and earth are
merely passive.... The world, including the whole of nature,
God and ma