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 of the Underworld, which was when Heracles shot him with an arrow as Hades was attempting to defend the city of Plyos. After he was shot, however, he traveled to Olympus to heal. Besides Heracles, the only other living people who ventured to the Underworld were also heroes: Odysseus, Aeneas (accompanied by the Sibyl), Orpheus, who Hades showed uncharacteristic mercy towards at Persephone's persuasion, who was moved by Orpheus' music, Theseus with Pirithous, and, in a late romance, Psyche. None of them were pleased with what they witnessed in the realm of the dead. In particular, the Greek war hero