It's almost ironic that in Asimov's Nightfall, madness is the inevitable fate of those who experience Darkness--regardless of their prior conditioning or present belief. When Darkness falls, everyone realises the The Prophecy was right after all: the last sun really will go dark, and the stars really will come out. But even those who expected this to happen are unprepared: the Scientists had no idea of the vastness of their universe, full of many thousands of stars; and the Cultists, still clinging to a false hope in the efficacy of their blind faith, go mad all the same, cursing the Scientists for ruining everything with their blind rationalism. Left unspoken in the short story version is the fate of those in the Hideout who had prepared for Nightfall with hundreds of torches to carry them, sanity intact, through the brief hours of Darkness and into the virtually infinite Light of the next Cycle.
Like so many of Asimov's stories, this one also contains a bit of the autobiographical--but this time, in foresight rather than hindsight. Asimov seems to be predicting, at the tender age of 21, his eventual encounter with the Darkness which, in his blind rationalism, he refuses to admit exists. He realises that Science, like his own rejected Religion of Rabbinic Judaism, can only foresee the End--not forestall it. He envisions himself, at some divinely decreed date, entering Darkness because, either by false belief or a desire for detachment from belief, he has failed to enter the Hideout.
Regardless of what he may have believed about it during his lifetime, Asimov irrevocably entered Darkness on April 6, 1992.
I'm reminded of the words of Philip J. King, in Five Minutes in Hell:
"Help me, Lord!" he begs while looking up and seeing the face of Jesus in the countenance of the Father. "Please don't let me perish! I've done many good works. Oh, give me one more chance! I believe now with all my heart. I was too proud to believe before. Please, Lord, please!"
The sincere outburst from the heartbroken man goes unheeded as the great Judge of heaven and earth solemnly declares, "Whosoever is not found written in the Book of Life shall be cast in to the Lake of Fire. Depart from Me, ye worker of iniquity, into everlasting fire, prepared for the devil and his angels."
The man, now too weak with despair to protest, does not resist as the angels carry him to the base of the throne. How he would like to get just one more glimpse of that beautiful city before his departure, but he is too blinded by his own tears to see it, even if he could.
He is astonished at the great strength of the angels as they cast him outward with terrific speed. Almost instantly everything is black—oppressively black—thick, misty black. There is not the tiniest ray of light—not even a flicker from the great white throne.
Already he must be an immeasurable distance from the throne. He feels himself falling faster and faster. Down, down he falls, away, way down.
"Please help me!" shouts the man into oppressive blackness. "Please, please help me!" Silence follows for what seems like many hours, and the man continues to fall.
Again the man shouts into the darkness. "Is there no one here to hear me? Am I the only one here? Please, will someone stop me from falling?"
The man is instantly startled as the voice of a demon replies, "Welcome to outer darkness, fellow-heir of damnation. Prepare to stay awhile."