by
another (or others) of the same nature--_e.g._ a given body is
called finite, because we can always conceive another body
enveloping it; but body is not limited by thought, nor thought by
body.

3. By substance I mean what exists in itself and is conceived by
itself; the conception of which, that is, does not involve the
conception of anything else as the cause of it.

4. By attribute I mean whatever the intellect perceives of substance
as constituting the essence of substance.

5. Mode is an affection of substance, or is that which is in
something else, by and through which it is conceived.

6. God is a being absolutely infinite; a substance consisting of
infinite attributes, each of which expresses his eternal and
infinite essence.

EXPLANATION.

I say _absolutely_ infinite, not infinite _suo genere_--for of what
is infinite _suo genere_ only, the attributes are not infinite but
finite; whereas what is infinite absolutely contains in its own
essence everything by which substance can be expressed, and which
involves no impossibility.

7. That thing is 'free' which exists by the sole necessity of its
own nature, and is determined in its operation by itself only. That
is 'not free' which is called into existence by something else, and
is determined in its operation according to a fixed and definite
method.

8. Eternity is existence itself, conceived as following necessarily
and solely from the definition of the thing which is eternal.

EXPLANATION.

Because existence of this kind is conceived as an eternal verity,
and, therefore, cannot be explained by duration, even though the
duration be without beginning or end.

So far the definitions; then follow the

AXIOMS.

1. All things that exist, exist either of themselves or in virtue of
something else.

2. What we cannot conceive of as existing in virtue of something
else, we must conceive through and in itself.

3. From a given cause an effect necessarily follows, and if there be
no given cause no effect can follow.

4. Things which have nothing in common with each other cannot be
understood through one another--_i.e._ the conception of one does
not involve the conception of the other.

5. To understand an effect implies that we understand the cause of
it.

6. A true idea is one