Full Idea
A proposition, unless it happens to be linguistic, does not itself contain words: it contains the entities indicated by words.
Gist of Idea
Proposition contain entities indicated by words, rather than the words themselves
Source
Bertrand Russell (The Principles of Mathematics [1903], §051)
Book Reference
Russell,Bertrand: 'Principles of Mathematics' [Routledge 1992], p.47
A Reaction
Russell says in his Preface that he took over this view of propositions from G.E. Moore. They are now known as 'Russellian' propositions, which are mainly distinguished by not being mental event, but by being complexes out in the world.