Heart of Stone (German: Das kalte Herz, literally "The Cold Heart") is a fairy tale written by Wilhelm Hauff. It was published in 1827 in a collection of fairy tales that take place within the narrative of The Spessart Inn. It formed the basis for the East German film Heart of Stone, released in 1950.
Despite taking over his late father's charcoal factory, Peter Marmot who goes by the name Coal-marmot Peter is not content with the dirty, exhausting, low paying and low status work. He dreams of prosperity and prestige. Then he hears about a forest spirit living in the Black Forest, the little glass-imp, who also goes by the name of Schatzhauser. The glass-imp grants three wishes to every person born on a Sunday between 11 am and 2 pm, just as Peter Marmot was, but he needs to be summoned with a specific poem. During the search for the little glass-imp, Peter comes across another forest spirit, the enormous and dangerous Dutch-Mike, who haunts the forest as an evil sorcerer on stormy nights. Peter, however, is able to escape him.
With the poem "Schatzhauser in the green firwood, thou art many hundreds of years old. Yours is the land where the firs stand, thou shalt only be seen by Sunday's children (the German version of Monday's Child)” Peter summons the little glass-imp, who grants him three wishes but with one condition: The third one will not be granted if his first two wishes are foolish. But right off the bat, Peter's first wish is foolish. For Peter wants to be able to dance better than the “dance floor king” and he wants to have just as much money as Ezekiel. Both are questionable role models of Peter's. His second wish is more reasonable. This time he asks for a big glass factory and enough money to run it. The little glass-imp points out that Peter should have wished for the brains necessary for that as well. The little glass-imp refuses to grant the third wish immediately so that Peter has one for later.
Peter's two wishes are granted and for a while, luck is on his side. He owns the most beautiful glass factory in the Black Forest, he dances better than everyone else and, when gambling, he has the same amount of money as Ezekiel does. Soon he becomes the most renowned man in the Black Forest. However, his lack of understanding of his chosen craft soon becomes obvious. He neglects his glass factory in favor of going gambling and finds himself in sudden debt. And it is only when he runs into Ezechiel at the tavern that he suddenly has as much money as Ezekiel has in his pockets.