Borges' most extended consideration of this question is his 1940 story
"Tlön, Uqbar, Orbis Tertius". Consider the objects called hrönir in the
alternative world described in this story. Hrönir, you'll recall, are
the objects in Tlön, but we are told they are "secondary objects" that
duplicate lost objects. Like shadows in Plato's cave, they exist by
virtue of their relation to prior (lost) entities; they are reflections
(reproductions) of something that was once "real" but no longer is.
These objects are "secondary" in the same sense that all visual and
verbal representations of material objects are secondary, but the
narrator tells us that hrönir, themselves replicas, may also replicate
themselves endlessly, each copy thus progressively removed from its
"real" object. Hrönir are secondary, and thus by definition figurative,
not material: we are told by the narrator that, quote: "All nouns
(man, coin, Thursday, Wednesday, rain) have only a metaphorical value"
(11). And in Tlön, there is yet another category of secondary objects
beyond the hrön: the narrator tells us that "Stranger and more perfect
than any hrön is the ur, which is a thing produced by suggestion, an
object brought into being by hope" (11). The ur is a conceptual object
even further removed from the material world than the hrön, and thus, it
seems, more real. Of course "Tlön, Uqbar, Orbis Tertius" is a
hilarious send-up of Berkeleyan idealism, for we understand that in
Tlön, "real" objects are non-existent; only ideal objects are real.
HOW THE "TRUE WORLD" FINALLY BECAME A FABLE. The History of an Error
1. The true world — attainable for the sage, the pious, the virtuous man; he lives in it, he is it.
(The oldest form of the idea, relatively sensible, simple, and persuasive. A circumlocution for the sentence, "I, Plato, am the
truth.")
2. The true world — unattainable for now, but promised for the sage, the pious, the virtuous man ("for the sinner who
repents").
(Progress of the idea: it becomes more subtle, insidious, incomprehensible — it becomes female, it becomes Christian.
)
3. The true world — unattainable, indemonstrable,
unpromisable; but the very thought of it — a consolation, an obligation, an imperative.
(At bottom, the old sun, but seen through mist and skepticism. The idea has become elusive, pale, Nordic, Königsbergian.)
4. The true world — unattainable? At any rate, unattained. And being unattained, also unknown. Consequently, not consoling,
redeeming, or obligating: how could something unknown obligate us?
(Gray morning. The first yawn of reason. The cockcrow of
positivism.)
5. The "true" world — an idea which is no longer
good for anything, not even obligating — an idea which has become useless and superfluous —consequently, a refuted idea: let us abolish it!
(Bright day; breakfast; return of bon sens and cheerfulness; Plato's embarrassed blush; pandemonium of all free spirits.)
6. The true world — we have abolished. What world has remained? The apparent one perhaps? But no! With the true world we have also abolished the apparent one.
(Noon; moment of the briefest shadow; end of the longest error; high point of humanity; INCIPIT ZARATHUSTRA.)