Silken Thread is based off a short story called "The Spider's Thread".
A Buddha meandering through Paradise sees through a crystal clear pond into hell, where he takes an interest in a sinner named Kandata. Kandata was a cold-blooded criminal who had only a single good deed to his name in all his years of living: he had refrained from stepping on a single spider while walking one day. The Buddha decided to lower a single spider's thread into hell, and tells Kandata to climb the thread to Paradise. Kandata, elated at this opportunity to escape Hell, eagerly made his way up. Halfway through, he tired and looked back and saw to his horror that others trapped in Hell were, too, climbing the thread. Fearing for the flimsiness of the thread, he angrily yelled at the others for endangering his method of escape and his alone, and in this act of uncharitable selfishness, the thread broke, sending all plunging back into Hell.