Everytime when you either hear a priest or a philosopher debate, you often found them quoting from the bible or their founder or beliefs. Why is that? Is that their hobby?
MAybe sometimes the politicians will quote from political father figures or constitutional or bill of rights.
It can help add credit to what they are saying, or sometimes what they want to say has already been said by someone else. Think of it if you where trying to express a idea but was having difficulty doing so but then you found X person had already elegantly expressed that idea wouldn’t it make sense to use that quote during your explanation?
It’s often used as an argument from authority. Politicians do it too. If Churchill (that Kurd gassin’, Gallipoli ruinin’, Black and Tan sendin’, miner oppressin’ A-hole) said it, it must be right, etc.
So I think we have discover how did the idea and invention of Rehetoric
come about. =D>
This can be done for several reasons -
to appeal to authority
to provide context
to clarify
to appeal to those that worship the published word
all of the above
Or my favorites: You need time to think of something to say, just can’t think of anything better to say and helps keep you from losing 