PART I: CONCERNING GOD.
Page: 5

they may through it be conceived. Whereas the only truth
substances can have, external to the intellect, must consist in
their existence, because they are conceived through themselves.
Therefore, 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 false (a little consideration will make this plain); or if
anyone affirmed that substance is created, it would be the same
as saying that a false idea was true--in short, the height of
absurdity. It must, then, necessarily be admitted that the
existence of substance as its essence is an eternal truth. And
we can hence conclude by another process of reasoning--that there
is but one such substance. I think that this may profitably be
done at once; and, in order to proceed regularly with the
demonstration, we must premise:--

+++++1. The true definition of a thing neither involves nor
expresses anything beyond the nature of the thing defined. From
this it follows that--

+++++2. No definition implies or expresses a certain number of
individuals, inasmuch as it expresses nothing beyond the nature
of the thing defined. For instance, the definition of a triangle
expresses nothing beyond the actual nature of a triangle: it
does not imply any fixed number of triangles.

+++++3. There is necessarily for each individual existent thing
a cause why it should exist.

+++++4. This cause of existence must either be contained in the
nature and definition of the thing defined, or must be postulated
apart from such definition.

It therefore follows that, if a given number of individual things
exist in nature, there must be some cause for the existence of
exactly that number, neither more nor less. For example, if
twenty men exist in the universe (for simplicity's sake, I will
suppose them existing simultaneously, and to have had no
predecessors), and we want to account for the existence of these
twenty men, it will not be enough to show the cause of human