@kennethamy,
I don't know, but it is one of the things that brought me to the Philosophy Forum. For some reason, I noticed that the lawful manner in which things exist, is something separate from the multitude of existing things. Then it occurred to me, that this is something very much like Pythagorism.
I think Aristotle made a mistake with his notion of 'substance'. What you are saying about something either existing, or not existing, is quite true of any
thing. A thing either exists, or it doesn't. But the nature of relationships between things is a different matter again. You can say a relationship exists, but really 'the relationship' is not an existing thing. It is not so much a thing, as the way in which things are related to each other. The way in which they are related has to do with ratio, and hence 'rationality'. This is what the Pythagorean insight was all about. It wasn't to do with 'stuff' or 'substance' or 'things', but the way in which everything was related through patterns and ratios.
Now this is another way of looking at the relationship between 'reality and appearance'. Of course, to the untutored eye, we see a vast array of things. But Pythagoras saw a vast set of numerical relations, which he called Kosmos. When seen this way, a lot of the mystification of metaphysics is due to the fact that Aristotle reified these relationships into the idea of 'substance'. I don't think either Pythagoras or Plato would have agreed with the idea of substance.