7. Of real existence agreeing to any idea.
Fourthly, The fourth and last sort is that of actual real existence agreeing
to any idea.
Within these four sorts of agreement or disagreement is, I suppose, contained all the knowledge we have, or are
capable of For all the inquiries we can make concerning any of our ideas, all that we know or can affirm
concerning any of them, is, That it is, or is not, the same with some other; that it does or does not always coexist
with some other idea in the same subject; that it has this or that relation with some other idea; or that it has a real
existence without the mind. Thus, "blue is not yellow," is of identity. "Two triangles upon equal bases between
two parallels are equal," is of relation. "Iron is susceptible of magnetical impressions," is of co-existence. "God
is," is of real existence. Though identity and co-existence are truly nothing but relations, yet they are such peculiar
ways of agreement or disagreement of our ideas, that they deserve well to be considered as distinct heads, and not
under relation in general; since they are so different grounds of affirmation and negation, as will easily appear to
any one, who will but reflect on what is said in several places of this Essay.
I should now proceed to examine the several degrees of our knowledge, but that it is necessary first, to consider
the different acceptations of the word knowledge.
