Full Idea
Judging or believing is a certain complex unity of which a mind is a constituent; if the remaining constituents, taken in the order which they have in the belief, form a complex unity, then the belief is true.
Gist of Idea
Truth is when a mental state corresponds to a complex unity of external constituents
Source
Bertrand Russell (Problems of Philosophy [1912], Ch.12)
Book Reference
Russell,Bertrand: 'The Problems of Philosophy' [OUP 1995], p.74
A Reaction
The modern label of 'congruence' for this view of truth makes it clearer. We aim to get a complex unity of constituents in our minds which are in the same 'order' as the constituents in the world. It is a good proposal, but leaves 'facts' as a problem.