There's a letter of Pliny the younger where he talks about how Tacitus (and, ahem, also Pliny himself) was so famous for his eloquence and learning that he could almost be recognized by it (or at least, that's my reading):

I never felt a more sensible pleasure than by an account which I lately received from Cornelius Tacitus. He informed me that, at the last Circensian games, he sat next to a Roman knight, who, after conversation had passed between them upon various points of learning, asked him, “Are you an Italian, or a provincial?” Tacitus replied, “Your acquaintance with literature must surely have informed you who I am.” “Pray, then, is it Tacitus or Pliny I am talking with?” I cannot express how highly I am pleased to find that our names are not so much the proper appellatives of men as a kind of distinction for learning herself; and that eloquence renders us known to those who would otherwise be ignorant of us.