Full Idea
If a relation between qualities is to be something, then clearly we will now require a new connecting relation. The links are united by a link, and this link has two ends, which require a fresh link to connect them to the old.
Gist of Idea
Relations must be linked to their qualities, but that implies an infinite regress of relations
Source
F.H. Bradley (Appearance and Reality [1893], p.28), quoted by Cynthia Macdonald - Varieties of Things Ch.6
Book Reference
Macdonald,Cynthia: 'Varieties of Things' [Blackwell 2005], p.247
A Reaction
That is: external relations generates an infinite regress, so relations must be internal. Russell launched his own philosophy with an attack on Bradley's idea. Personally I take how two things 'relate' to one another as one of the deepest of mysteries.