The fables remain a popular choice for moral education of children today. Many stories included in Aesop's Fables, such as "The Fox and the Grapes" (from which the idiom "sour grapes" was derived), "The Tortoise and the Hare" (see Zeno's paradoxes) and "The Shepherd Boy and the Wolf" (also known as "The Boy Who Cried Wolf"), are well-known throughout the world.