Proverbs

[Bernd Heine]

Looking through a range of grammars of languages across the world I am 
surprised that proverbs are largely or entirely ignored in grammatical 
descriptions. They appear occasionally in the exemplification of 
structures but are essentially never discussed, e.g., as a discourse 
type, or as illustrating a special kind of morphosyntactic structure or 
relationship between form and meaning.
To be sure, I could think of a number of reasons for that, but I find 
none of them entirely convincing. Why should proverbs not have a place 
in a (comprehensive) reference grammar? After all, they appear to occur 
in all languages that have been appropriately documented, and they are 
part of the knowledge speakers have about their language. Please advise.
Bernd