Hmm …

… Saul Kripke’s chains of communication | Footnotes to Plato. (Hat tip, Dave Lull.)

“Christopher Columbus” undoubtedly denotes a fifteenth-century Genoese explorer; but most English speakers don’t have any description in mind; or at any rate none that uniquely specifies any fifteenth-century Genoese explorer. “The first European to visit America” probably specifies some tenth-century Viking. “A fifteenth-century Italian explorer” doesn’t specify anyone. 

True of most people, perhaps, but not true of someone who has read Samuel Eliot Morison's Admiral of the Ocean Sea. Words have greater meaning for those who have greater knowledge.