"The Canterbury Tales" is a collection of stories built around a frame narrative or frame tale, a common and already long established genre of its period. Chaucer's "Tales" differs from most other story "collections" in this genre chiefly in its intense variation. Most story collections focused on a theme, usually a religious one. Even in the "Decameron", storytellers are encouraged to stick to the theme decided on for the day. The idea of a pilgrimage to get such a diverse collection of people together for literary purposes was also unprecedented, though "the association of pilgrims and storytelling was a familiar one". Introducing a competition among the tales encourages the reader to compare the tales in all their variety, and allows Chaucer to showcase the breadth of his skill in different genres and literary forms.