3.261 Every sign that has a definition signifies via the signs that serve
to define it; and the definitions point the way. Two signs cannot signify
in the same manner if one is primitive and the other is defined by means of
primitive signs. Names cannot be anatomized by means of definitions. (Nor
can any sign that has a meaning independently and on its own.)


3.262 What signs fail to express, their application shows. What signs slur
over, their application says clearly.


3.263 The meanings of primitive signs can be explained by means of
elucidations. Elucidations are propositions that stood if the meanings of
those signs are already known.


3.3 Only propositions have sense; only in the nexus of a proposition does a
name have meaning.


3.31 I call any part of a proposition that characterizes its sense an
expression (or a symbol). (A proposition is itself an expression.)
Everything essential to their sense that propositions can have in common
with one another is an expression. An expression is the mark of a form and
a content.


3.311 An expression presupposes the forms of all the propositions in which
it can occur. It is the common characteristic mark of a class of
propositions.