Full Idea
Contingency derives from the fact that a sentence containing a verb in the present tense - or sometimes in the past or the future - changes its meaning continually as the present changes, and stands for different propositions at different times.
Gist of Idea
Contingency arises from tensed verbs changing the propositions to which they refer
Source
Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.26)
Book Reference
Russell,Bertrand: 'Essays in Analysis', ed/tr. Lackey,Douglas [George Braziller 1973], p.26
A Reaction
This immediately strikes me as a bad example of the linguistic approach to philosophy. As if we (like any animal) didn't have an apprehension prior to any language that most parts of experience are capable of change.