Full Idea
In the case of vision, sense data are a kind of inner picture show which itself only indirectly represents aspects of the external world.
Gist of Idea
Visual sense data are an inner picture show which represents the world
Source
Simon Blackburn (Oxford Dictionary of Philosophy [1994], p.347)
Book Reference
Blackburn,Simon: 'Oxford Dictionary of Philosophy' [OUP 1996], p.347
A Reaction
I'm unsure whether this is correct. Russell says the 'roughness' of the table is the sense datum. If it is even a possibility that there are unsensed sense-data, then they cannot be an aspect of the mind, as Blackburn is suggesting they are.