What Dreams May Come in the book are derived from my wide range of reading." One of Matheson's influences was Harold W. Percival, an adherent of Theosophy, a belief system with a strong Eastern and Hindu influence. The story also shares the same theme of the ancient Greek myth Orpheus and Eurydice, in which the gifted musician makes a challenging journey to Hell to retrieve his wife. One character quotes from the writings of 18th century Christian mystic Emanuel Swedenborg. Matheson bases his descriptions of the death experience itself on studies by Elisabeth Kübler-Ross and Raymond Moody. When reading these accounts, Matheson found that
Hades left Helen with Theseus' mother, Aethra, and traveled to the Underworld. Hades knew of their plan to capture his wife, so he pretended to offer them hospitality and set a feast; as soon as the pair sat down, snakes coiled around their feet and held them there. Theseus was eventually rescued by Heracles but Pirithous remained trapped as punishment for daring to seek the wife of a god for his own. Heracles' final labour was to capture Cerberus. First, Heracles went to Eleusis to be initiated into the Eleusinian Mysteries. He did this to absolve himself of guilt for killing