Concept

Underworld

Overview

supernatural realm, usually beneath the earth, in various mythologies

Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).

Found by search and not yet checked by a person; they may only mention the idea in passing.

Of the various ideas of the beyond that successively arise in this development, those regarding the underworld are the most common and the most permanent. This is probably due in no small measure to the custom of _burying the corpse_.
Wilhelm Max Wundt, Elements of Folk Psychology Outline of a Psychological History of the Development of Mankind
States what Underworld is; names Underworld several times.
Read the chapter · Open in the reader
Possibly! To rise beyond this “possibly” we should indeed have been guests in the Underworld, playing at dice and betting with Proserpine at the table of the goddess herself.
Friedrich Wilhelm Nietzsche, The Dawn of Day
States what Underworld is; names Underworld.
Read the chapter · Open in the reader
Such is my will: And since 'tis my will, All goes as I wish-- That was my final wisdom: I willed what I must, And thus I forced every "must,"-- Since then has been for me no "must." Deceit Is war's whole art The fox's skin Is my secret shirt of mail We of the new underworld Grub for new treasures. Godless it seemed to the ancients To disturb the earth's bowels for treasures And once more this godlessness revives…
Friedrich Wilhelm Nietzsche, Ecce Homo Complete Works, Volume Seventeen
States what Underworld is; names Underworld.
Read the chapter · Open in the reader