Full Idea
There may be a substance at the centre of an object, but is no reason to think so, since the group of events making up the object will produce exactly the same percepts; so the substance, if there is one, is an abstract possibility irrelevant to science.
Gist of Idea
An object produces the same percepts with or without a substance, so that is irrelevant to science
Source
Bertrand Russell (The Analysis of Matter [1927], 23)
Book Reference
Russell,Bertrand: 'The Analysis of Matter' [Routledge 1992], p.244
A Reaction
All empiricists (as Russell is in this passage) seem to neglect inference to the best explanation. Things can be indirectly testable, and I would say that there are genuine general entities which are too close to abstraction to ever be testable.
Related Idea
Idea 14732 A perceived physical object is events grouped around a centre [Russell]