2 What can be shown, cannot be said.

4.1213 Now, too, we understand our feeling that once we have a
sign-language in which everything is all right, we already have a
correct logical point of view.

4.122 In a certain sense we can talk about formal properties of objects
and states of affairs, or, in the case of facts, about structural
properties: and in the same sense about formal relations and structural
relations. (Instead of 'structural property' I also say 'internal
property'; instead of 'structural relation', 'internal relation'. I
introduce these expressions in order to indicate the source of the
confusion between internal relations and relations proper (external
relations), which is very widespread among philosophers.) It is
impossible, however, to assert by means of propositions that such
internal properties and relations obtain: rather, this makes itself
manifest in the propositions that represent the relevant states of
affairs and are concerned with the relevant objects.

4.1221 An internal property of a fact can also be bed a feature of that
fact (in the sense in which we speak of facial features, for example).

4.123 A property is internal if it is unthinkable that its object should
not possess it. (This shade of blue and that one stand, eo ipso, in the
internal relation of lighter to darker. It is unthinkable that these two
objects should not stand in this relation.) (Here the shifting use
of the word 'object' corresponds to the shifting use of the words
'property' and 'relation'.)

4.124 The existence of an internal property of a possible situation is
not expressed by means of a proposition: rather, it expresses itself
in the proposition representing the situation, by means of an internal
property of that proposition. It would be just as nonsensical to assert
that a proposition had a formal property as to deny it.

4.1241 It is impossible to distinguish forms from one another by
saying that one has this property and another that property: for this
presupposes that it makes sense to ascribe either property to either
form.

4.125 The existence of an internal relation between possible situations
expresses itself in language by means of an internal relation between
the propositions representing them.

4.1251 Here we have the answer to the vexed question 'whether all
relations are internal or external'.

4.1252 I call a series that is ordered by an internal relation a series
of form