== Referential Indexicality == 

 I do not get the explanation about Unicorns drink ambrosia. 
 To me, the point of that example would have to have something to do with the fact that Unicorns and Ambrosia don't exist. But that would make it more an example of discussions about truth assessment (is it true or not that Unicorns drink Ambrosia and what's there to be said about it given that both do not exist) then of referential content? 
 Anyway in the explanation nothing is said about Unicorns and ambrosia being non-existent while that should be at least commented upon given that it is obvious the case if one uses these concepts in particular.