"The Moon is made of green cheese" is a statement referring to a fanciful belief that the Moon is composed of cheese. In its original formulation as a proverb and metaphor for credulity with roots in fable, this refers to the perception of a simpleton who sees a reflection of the Moon in water and mistakes it for a round cheese wheel. It is widespread as a folkloric motif among many of the world's cultures, and the notion has also found its way into children's folklore and modern popular culture. The phrase "green cheese" in the common version of this proverb (sometimes "cream cheese" is used), may refer to a young, unripe cheese or to cheese with a greenish tint. There was never an actual historical popular belief that the Moon is made of green cheese (cf. Flat Earth and the myth of the Flat Earth). It was typically used as an example of extreme credulity, a meaning that was clear and commonly understood as early as 1638. Fable There exists a family of stories, in comparative mythology in diverse countries that concern a simpleton who sees a reflection of the Moon and mistakes it for a round cheese: The Wolf and the Fox story type This folkloric motif is first recorded in literature during the High Middle Ages by the French rabbi Rashi with a Rabbinic parable in his commentary weaving together three Biblical quotations given in the main text (including one on "sour grapes") into a reconstruction of some of the Talmudic Rabbi Meir's supposed three hundred fox fables ("משלות שועלים", in later works "משלי שועלים"), in the tractate Sanhedrin: Rashi as the first literary reference may reflect the well-known beast fable tradition of French folklore or a more obscure such tradition in Jewish folklore (see also the tradition in Berechiah ha-Nakdan); the near-contemporary Iraqi rabbi Hai Gaon also reconstructed this Rabbi Meir tale, sharing some elements of Rashi's story, but with a lion caught in a trapping pit rather than a wolf in a well – however, Rashi may have actively "adapted contemporary [French] folklore to the [T]almudic passage", as was homiletically practiced in different Jewish communities. Though the tale itself is probably of non-Jewish European origin, Rashi's form and elements are likely closer to the original in oral folklore than the somewhat later variation recorded featuring Reynard. Rashi's version already includes the fox, the wolf, the