The idiom later became common in many languages and appeared in Slavic folk tales. In one such tale, the beautiful princess tests the ardor and resourcefulness of her suitor by sending him out into the wilderness to find and bring back the one fantastical luxury she does not have: bird's milk. In the fairy tale Little Hare by Aleksey Remizov (who wrote many imitations of traditional Slavic folk tales), the magic bird Gagana produces milk.
The idiom spread across multiple languages and appeared in Slavic folklore. In one Slavic folktale, the princess tests her suitor's passion and resourcefulness by sending him to find and bring back the unique luxury she lacks: bird's milk. Aleksey Remizov, who wrote many imitations of traditional Slavic folktales, includes a fairy tale titled Little Hare where a magical bird named Gagana produces milk.