something external to itself to a fixed and definite method of
existence or action.

VIII. By eternity, I mean existence itself, in so far as it is
conceived necessarily to follow solely from the definition of
that which is eternal.

Explanation--Existence of this kind is conceived as an eternal
truth, like the essence of a thing, and, therefore, cannot be
explained by means of continuance or time, though continuance may
be conceived without a beginning or end.

AXIOMS.

I. Everything which exists, exists either in itself or in
something else.

II. That which cannot be conceived through anything else must be
conceived through itself.

III. From a given definite cause an effect necessarily follows;
and, on the other hand, if no definite cause be granted, it is
impossible that an effect can follow.

IV. The knowledge of an effect depends on and involves the
knowledge of a cause.

V. Things which have nothing in common cannot be understood, the
one by means of the other; the conception of one does not
involve the conception of the other.

VI. A true idea must correspond with its ideate or object.

VII. If a thing can be conceived as non--existing, its essence
does not involve existence.

PROPOSITIONS.

PROP. I. Substance is by nature prior to its modifications.

Proof.--This is clear from Deff. iii. and v.

PROP. II. Two substances, whose attributes are different, have
nothing in common.

Proof.--Also evident from Def. iii. For each must exist in
itself, and be conceived through itself; in other words, the
conception of one does not imply the conception of the other.

PROP. III. Things which have nothing in common cannot be one the
cause of the other.

Proof.--If they have nothing in common, it follows that one
cannot be apprehended by means of the other (Ax. v.), and,
therefore, one cannot be the cause of the other (Ax. iv.).
Q.E.D.

PROP. IV. Two or more distinct things are distinguished one from
the other, either by the difference of the attributes of the
substances, or by the difference of their modifications.

Proof.--Everything which exists, exists either in itself or in
something else (Ax. i.),--that is (by Deff. iii. and v.), nothing
is granted in addition to the understanding, except substance and
its modifications. Nothing is, therefore, given besides the
understanding, by which several things may be distinguished one
from the other, except the substances, or, in oth