I have heard that theoretically you can classify all things you can possibly talk/write about into 3 categories i.e. be, do and have. People and things can be something, do something and have something, but that is it. (Beliefs, experiences and intentions fall under the Have category; we have beliefs, experiences and intentions.)
What is the significance of this? Is it true (is it possible to categorize all sentences into these 3 categories with nothing left over)?