To know the history of an idiom can be useful and interesting, but is not necessary to be able to use the idiom properly. For example, most native British English speakers know that "No room to swing a cat" means "there was not much space" and can use the idiom properly. However, few know this is because 200 years ago sailors were punished by being whipped with a "cat o' nine tails". A big space was cleared on the ship so that the person doing the whipping had room to "swing the cat".