Full Idea
The world of particulars is a six-dimensional space, where six co-ordinates will be required to assign the position of any particular, three to assign its position in its own space, and three to assign the position of its space among the other spaces.
Gist of Idea
Six dimensions are needed for a particular, three within its own space, and three to locate that space
Source
Bertrand Russell (The Ultimate Constituents of Matter [1915], p.134)
Book Reference
Russell,Bertrand: 'Mysticism and Logic' [Unwin 1989], p.134
A Reaction
Not a proposal that has caught on. One might connect the idea with the notion of 'frames of reference' in Einstein's Special Theory. Inside a frame of reference, three co-ordinates are needed; but where is the frame of reference?