That which is, is. It's pretty hard to argue with that. Does that mean conversely, that that which is not, is not? Actually, not. My contention is that that which is not, is. In order not to exist, something must have existence. Otherwise you could not even make the statement that it is not; note that you have to use that two-letter word in order to do so. Once something is, it can blink out into a state of non-existence, but then its non-existent status is maintained in Being. Its isness, in other words, has no time property. That which was, is, and that which will be, is. As well as that which is, of course. By the way, the word maya means "that which is not." And there's plenty of that around, as we know.