Good Beings, Corruptible Beings

I think Hannah brings up an important chapter below when she discusses Augustine's view that "every being is good." This chapter definitely brings up questions that we have been discussing, such as: "what is evil?," "did God create it?," "can evil exist in the absence of all good?"

Morgan, in her comment, suggests that Hannah is interpreting St. Augustine's conclusion about good and evil as different from our own. Hannah says: "We finally came to the conclusion that you can't have an evil without a good, while here, Augustine says you cannot be evil, unless there was some good to turn into evil." Since Hannah uses the words "while here" it does seem that she is suggesting Augustine would disagree with our own conclusion, but then her statement of what Augustine believes doesn't seem to me to be that different from our own. I'd be curious to hear more from Hannah about how she thinks Augustine's conclusion contradicts the idea that "you can't have evil without a good." It seems to me that what Augustine is saying is that everything that exists (in other words, everything that is a "being") must be good, because it is either the supreme good (God) and thus incorruptible, or it is something corruptible. If it is corruptible, then that means it is good, for you can't corrupt something that is completely evil, only something that is good (after all, that's what corruption means: to make what is good less so). According to this argument, then, every being is good. If so, then to the extent that anything exists, there would be some good. If what exists were at any point entirely corrupted, then there would be nothing good left, and since "every being is good" then that means there would be nothing left at all. In other words, you can't have evil if there is nothing good, simply because if there is nothing good left, then there would be nothing at all.

That's how I understand Augustine's argument. Do you have a different understanding of it? Whether you do or you don't, do you think it is a logical argument? Or do you think it is flawed in some way?