d that which is in itself and is conceived by
means of itself, _i.e._, that the conception of which can be formed without
the aid of the conception of any other thing." _Per substantiam intelligo
id, quod in se est et per se concipitur; hoc est id, cujus conceptus
non indiget conceptu alterius rei, a quo formari debeat_. An absolutely
self-dependent being can neither be limited (since, in respect to its
limits, it would be dependent on the limiting being), nor occur more than
once in the world. Infinity follows from its self-dependence, and its
uniqueness from its infinity.

Substance is the being which is dependent on nothing and on which
everything depends; which, itself uncaused, effects all else; which
presupposes nothing, but itself constitutes the presupposition of all that
is: it is pure being, primal being, the cause of itself and of all. Thus in
Spinoza the being which is without presuppositions is brought into the most
intimate relation with the fullness of multiform existence, not coldly and
abstractly exalted above it, as by the ancient Eleatics. Substance is the
being in (not above) things, that in them which constitutes their reality,
which supports and produces them. As the cause of all things Spinoza calls
it God, although he is conscious that he understands by the term something
quite different from the Christians. God does not mean for him a
transcendent, personal spirit, but only the _ens absolute infinitum (def.
sexta)_, the essential heart of things: _Deus sive substantia_.

How do things proceed from God? Neither by creation nor by emanation. He
does not put them forth from himself, they do not tear themselves free from
him, but they follow out of the necessary nature of God, as it follows from
the nature of the triangle that the sum of its angles is equal to two right
angles (I. _prop_. 17, _schol_.). They do not come out from him, but remain
in him; just this fact that they are in another, in God, constitutes their
lack of self-dependence (I. _prop_. 18, _dem.: nulla res, quae extra Deum
in se sit_). God is their inner, indwelling cause (_causa immanens, non
vero transiens_.--I. _prop_. 18), is not a transcendent creator, but
_natura naturans_, over against the sum of finite beings, _natura naturata_
(I. _prop_. 29, _schol_.): _Deus sive natura_.

Since nothing exists out of God, his actions do not follow from external
necessity, are not constrained, but he is free cause, free in the sense
that