How did Duke Zhou see grandma smoking?

Dream interpretation is a very complicated subject, which contains a lot of information about dreamers. For example, did your grandmother die? Does she like smoking? Do dreamers like smoking? These are simple questions, and there are more complicated ones. Suppose in your dream, grandma is just a metonymy, which is even more troublesome. It is also possible that smoking is metonymy, so dream interpretation is not that simple.