"Lisa the Skeptic" is the eighth episode of The Simpsons' ninth season, first aired in November 1997. On an archaeological dig with her class, Lisa discovers a skeleton that resembles an angel. All of the townspeople believe that the skeleton actually came from an angel, but skeptical Lisa attempts to persuade them that there must be a rational scientific explanation, asking the American paleontologist Stephen Jay Gould to test a sample. After Gould tells Lisa that the tests were inconclusive, she compares the belief in angels to the belief in unicorns and leprechauns and in response, Springfield's religious zealots go on a rampage to destroy all scientific institutions. The episode's writer David X. Cohen (pictured) developed the idea after visiting the American Museum of Natural History, and decided to loosely parallel themes from the Scopes Monkey Trial. The episode received generally positive reviews. It has been discussed in the context of virtual reality, ontology, existentialism, and skepticism; it has also been used in Christian religious education classes to initiate discussion about angels, skepticism, science, and faith.