within his fixed and necessary constitution. It is evident that if such
a God exist, nothing can fall outside of him. One such substance must be
the only substance. But upon what grounds are we to assert God's
existence?

To proceed further with Spinoza's philosophy we must introduce two terms
which are scarcely less fundamental in his system than that of
substance. The one of these is "attribute," by which he means _kind_ or
general property; the other is "mode," by which he means _case_ or
individual thing. Spinoza's proof of God consists in showing that no
single mode, single attribute, or finite group of modes or attributes,
can be a substance; but only an infinite system of all modes of all
attributes. Translated into common speech this means that neither kinds
nor cases, nor special groups of either, can stand alone and be of
themselves, but only the unity of all possible cases of all possible
kinds.

The argument concerning the possible substantiality of the case or
individual thing is relatively simple. Suppose an attribute or kind,
_A_, of which there are cases _am_{1}, _am_{2}, _am_{3}, etc. The
number of cases is never involved in the nature of the kind, as is seen
for example in the fact that the definition of triangle prescribes no
special number of individual triangles. Hence _am_{1}, _am_{2},
_am_{3}, etc., must be explained by something outside of their nature.
Their being cases of _A_ does not account for their existing severally.
This is Spinoza's statement of the argument that individual events, such
as motions or sensations, are not self-dependent, but belong to a
context of like events which are mutually dependent.

The question of the attribute is more difficult. Why may not an
attribute as a complete domain of interdependent events, itself be
independent or substantial? Spinoza's predecessor, Descartes, had
maintained precisely that thesis in behalf of the domain of thought and
the domain of space. Spinoza's answer rests upon the famous ontological
argument, inherited from scholasticism and generally accepted in the
first period of modern philosophy. The evidence of existence, he
declares, is clear and distinct conceivability.

"For a person to say that he has a clear and distinct--that
is, a true--idea of a substance, but that he is not sure
whether such substance exists, would be the same as if he said
that he had a true idea, but was not sure whether or no it was