literature

[swatson]

words or phrases that are used again and again in various works in the oral tradition are called

[starryxskyz]

A motif.
http://www.answers.com/motif

[another-view]

clich�s?

[swedeheart]

Might refer to memes. Possibly. But if it does it's an inadequate definition, so meme is probably not what they/you are looking for.