The thought is the significant proposition.
4.001 - 4.003
4.01 - 4.06

4.1 * (2)*
A proposition presents the existence and non-existence of atomic facts.

4.2 * (8)*
The sense of a proposition is its agreement and disagreement with the possibilities of the existence
and non-existence of the atomic facts.

4.3 * (1)*
The truth-possibilities of the elementary propositions mean the possibilities of the existence and non-existence of the atomic facts.

4.4 * (6)*
A proposition is the expression of agreement and disagreement with the truth-possibilities of the elementary propositions.

4.5 * (3)*
Now it appears to be possible to give the most general form of proposition; i.e. to give a description of the propositions
of *some one* sign language, so that every possible sense can be expressed by a symbol,
which falls under the description, and so that every symbol which falls under the description
can express a sense, if the meanings of the names are chosen accordingly.

It is clear that in the description of the most general form of proposition
*
only* what is essential to it may be described -- otherwise it would not be the most general form.