Full Idea
I hold that what is true or false is not in general mental, and requiring a name for the true or false as such, this name can scarcely be other than 'propositions'.
Gist of Idea
What is true or false is not mental, and is best called 'propositions'
Source
Bertrand Russell (The Principles of Mathematics [1903], Pref)
Book Reference
Russell,Bertrand: 'Principles of Mathematics' [Routledge 1992], p.-19
A Reaction
This is the Fregean and logicians' dream that that there is some fixed eternal realm of the true and the false. I think true and false concern the mental. We can talk about the 'facts' which are independent of minds, but not the 'truth'.