Full Idea
There is beyond a doubt nothing real in the category of Relation, except what is a thing from another category.
Gist of Idea
The only reality in the category of Relation is things from another category
Source
Henry of Ghent (Quodlibeta [1284], VII:1-2), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 12.3
Book Reference
Pasnau,Robert: 'Metaphysical Themes 1274-1671' [OUP 2011], p.233
A Reaction
This seems to have been the fairly orthodox scholastic view of relations.