The Roseicrucians were everywhere, aided by the fact that they didn't exist. - Umberto Eco

This has nothing to do with realism (even if it explains also realism). A completely real world can be constructed, in which asses fly and princesses are restored to life by a kiss, but that world, purely possible and unrealistic, must exist according to structures defined at the outset (we have to know whether it is a world where a princess can be restored to life only by the kiss of a prince, or also by that of a witch, and whether the princess's kiss tranforms only frogs into princes or also, for example, armadillos).

But Paris, all in all, isn't what it used o be, ever since that pencil sharpener, the Eiffel Tower, has been sticking up in the distance, visible from every angle.

What is a symbol? Etymologically speaking, the word σύμβολον comes from σνμβάλλω, to throw-with, to make something coincide with something else: a symbol was originally an identification mark made up of two halves of a coin or of a medal. Two halves of the same thing, either one standing for the other, both becoming, however, fully effective only when they matched to make up, again, the original whole. … in the original concept of symbol, there is the suggestion of a final recomposition. Etymologies, however, do not necessarily tell the truth — or, at least, they tell the truth, in terms of historical, not of structural, semantics. What is frequently appreciated in many so-called symbols is exactly their vagueness, their openness, their fruitful ineffectiveness to express a 'final' meaning, so that with symbols and by symbols one indicates what is always beyond one's reach.