Full Idea
Reality is one. It must be simple because plurality, taken as real, contradicts itself. Plurality implies relations, and, through its relations it unwillingly asserts always a superior unity.
Gist of Idea
Reality is one, because plurality implies relations, and they assert a superior unity
Source
F.H. Bradley (Appearance and Reality [1893], p.519), quoted by A.C. Grayling - Russell Ch.2
Book Reference
Grayling,A.C.: 'Russell' [OUP 1996], p.26
A Reaction
This argument depends on a belief in 'internal' relations, which Russell famously attacked. If an internal feature of every separate item was its relation to other things, then I suppose Bradley would be right. But it isn't, and he isn't.