le in fact the window is not to the left of the door, the proposition
does not result from the objective by the mere substitution of images
for their prototypes. Thus in this unusually simple case we can say that
a true proposition "corresponds" to its objective in a formal sense in
which a false proposition does not. Perhaps it may be possible to modify
this notion of formal correspondence in such a way as to be more widely
applicable, but if so, the modifications required will be by no means
slight. The reasons for this must now be considered.

To begin with, the simple type of correspondence we have been exhibiting
can hardly occur when words are substituted for images, because, in
word-propositions, relations are usually expressed by words, which are
not themselves relations. Take such a proposition as "Socrates
precedes Plato." Here the word "precedes" is just as solid as the words
"Socrates" and "Plato"; it MEANS a relation, but is not a relation. Thus
the objective which makes our proposition true consists of TWO terms
with a relation between them, whereas our proposition consists of THREE
terms with a relation of order between them. Of course, it would be
perfectly possible, theoretically, to indicate a few chosen relations,
not by words, but by relations between the other words. "Socrates-Plato"
might be used to mean "Socrates precedes Plato"; "Plato-Socrates" might
be used to mean "Plato was born before Socrates and died after him"; and
so on. But the possibilities of such a method would be very limited. For
aught I know, there may be languages that use it, but they are not among
the languages with which I am acquainted. And in any case, in view of
the multiplicity of relations that we wish to express, no language could
advance far without words for relations. But as soon as we have words
for relations, word-propositions have necessarily more terms than the
facts to which they refer, and cannot therefore correspond so simply
with their objectives as some image-propositions can.

The consideration of negative propositions and negative facts introduces
further complications. An image-proposition is necessarily positive:
we can image the window to the left of the door, or to the right of the
door, but we can form no image of the bare negative "the window not to
the left of the door." We can DISBELIEVE the image-proposition expressed
by "the window to the left of the door," and our disbelief will be true
if the wi