Full Idea
We do not know, except by means of more or less precarious inferences, whether the objects which are at one time sense-data continue to exist at times when they are not data.
Gist of Idea
We do not know whether sense-data exist as objects when they are not data
Source
Bertrand Russell (The Relation of Sense-Data to Physics [1914], §II)
Book Reference
Russell,Bertrand: 'Mysticism and Logic' [Unwin 1989], p.142
A Reaction
Note that he actually refers to sense-data as 'objects'. It shows how thoroughly reified they are in his theory if they have the possibility of independent existence. This invites the question 'what are they made of?'