Brief reference, without explanation, to a person, a text, a myth, or a fact known outside the work, which carries with it the meaning of that other story.
In One, No One, and One Hundred Thousand
The problem is always this, gentlemen: that all of them should have to be called by that single name of Julius Caesar, and that in one male body so many, and even a woman, should have to cohabit.
"Julius Caesar" appears without explanation, as an example the reader already knows. The reference serves as proof that a single name can house many men, even "a woman," as the sentence itself says.