Synthesized answer
The provided passages state that Jorge Luis Borges's collection of short stories, "Ficciones," often employs the labyrinth as a literary device [Passage 1]. This device is used to explore his ideas on all aspects of human life and endeavor [Passage 1].
The passages indicate that "Ficciones" contains a story titled "[Tlön, Uqbar, Orbis Tertius]" [Passage 1]. However, the passages do not elaborate on the specific key concepts within "Ficciones" or how to explain them in my own words. Therefore, I cannot provide a comprehensive explanation of the key concepts.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: Ficciones by Jorge Luis Borges Description: A collection of his short stories in which Borges often uses the labyrinth as a literary device to expound his ideas on all aspects of human life and endeavor. ---------- Contains: [Tlön, Uqbar, Orbis Tertius](https://openlibrary.org/works/OL444914W)