Full Idea
Some philosophers have thought that a relation, being essentially two-termed, cannot hold between a thing and itself. This position is plainly absurd ('he is his own worst enemy'). Identity is nothing but the smallest reflexive relation.
Gist of Idea
A relation can clearly be reflexive, and identity is the smallest reflexive relation
Source
Saul A. Kripke (Naming and Necessity notes and addenda [1972], note 50)
Book Reference
Kripke,Saul: 'Naming and Necessity' [Blackwell 1980], p.109
A Reaction
I have no idea what 'smallest' means here. I can't be 'to the left of myself', so not all of my relations can be reflexive. I just don't understand what it means to say something is 'identical with itself'. You've got the thing - what have you added?