More on that pesky Greek present imperative

It goes without saying that an expression which indicates that the speaker assumes a close connection between the situation as he sees it, and the action he orders, sometimes has a very emotional ring. Therefore the present imperative is used especially by persons who are short-tempered, or have an overbearing character, because such people want an action to start as soon as, in their view, the situation requires it. These present imperatives are often derived from instantaneous verbs.—The Greek Imperative, page 54

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Unless they aren't...which is the problem I'm having with this book. He is seeking an overarching theory, but there are so many subpoints that don't fit, so he creates little categories for them. In the end, we have a list of things the imperative can mean. Is that an overarching theory?!

Don't misunderstand, the book is very helpful and has good stuff. But, how do you decide which category that particular imperative fits? And is that really what we want to do? That's going back to the decoding form of language learning...
</idle musing>