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.
- -- Wittgenstein, Ludwig