Full Idea
The property of a relation which insures that it holds between a term and itself is called by Peano 'reflexiveness', and he has shown, contrary to what was previously believed, that this property cannot be inferred from symmetry and transitiveness.
Gist of Idea
'Reflexiveness' holds between a term and itself, and cannot be inferred from symmetry and transitiveness
Source
Bertrand Russell (The Principles of Mathematics [1903], §209)
Book Reference
Russell,Bertrand: 'Principles of Mathematics' [Routledge 1992], p.219
A Reaction
So we might say 'this is a sentence' has a reflexive relation, and 'this is a wasp' does not. While there are plenty of examples of mental properties with this property, I'm not sure that it makes much sense of a physical object. Indexicality...