Full Idea
A belief is true when there is a corresponding fact, and is false when there is no corresponding fact.
Gist of Idea
Beliefs are true if they have corresponding facts, and false if they don't
Source
Bertrand Russell (Problems of Philosophy [1912], Ch.12)
Book Reference
Russell,Bertrand: 'The Problems of Philosophy' [OUP 1995], p.75
A Reaction
Russell tries to explain a 'fact' as a complex unity of constituents with a certain order among them. There is an obvious problem that some of the 'orders' in the world are imposed on it by the mind. But we don't invent 'D's love for C'.