Full Idea
It is quite clear that propositions are not what you might call 'real'; if you were making an inventory of the world, propositions would not come in.
Clarification
An 'inventory' is a catalogue
Gist of Idea
An inventory of the world does not need to include propositions
Source
Bertrand Russell (The Philosophy of Logical Atomism [1918], §III)
Book Reference
Russell,Bertrand: 'Russell's Logical Atomism', ed/tr. Pears,David [Fontana 1972], p.70
A Reaction
I am not clear why this is "quite clear". Propositions might even turn up in our ontology as physical objects (brain states). He says beliefs are real, but if you can't have a belief without a proposition, and they aren't real, you are in trouble.