I'll offer my two cents on this topic. On page 157 of the book
Mastering the Core Teachings of the Buddha which I downloaded a few minutes ago from the Integrated Daniel website, where he is attempting to explain anatta:
You see, as all phenomena are observed, they cannot possibly be the observer. Thus, the observer, which is awareness and not any of the phenomena pretending to be it, cannot possibly be a phenomenon and thus is not localized and doesn't exist. This is no-self.
I agree until the part I've put in bolded italics, which is where I think he goes horribly awry. [Well actually, I wouldn't say that the observer "is awareness" either.] And then it gets worse:
However, all of these phenomena are actually us from the point of view of non-duality and interconnectedness, as the illusion of duality is just an illusion.
This is clear Mahayana, but not what Buddha says in the Pali Canon. MN 22 "Therefore, monks, give up whatever is not yours. Your giving it up will for a long time bring you welfare and happiness. What is it that is not yours?..[Form, Feeling, Perception, Dispositions, Sensory Consciousness]...Give it up! Your giving it up will for a long time bring you welfare and happiness." That is a clear duality between you/yours and not-you/not-yours. That duality is largely the whole point of Buddha's Buddhism.
But, the Integrated Daniel continues:
When the illusion of duality permanently collapses in final awakening, all that is left is all of these phenomena, which is True Self, i.e. the lack of a separate self and thus just all of this as it is. Remember, however, that no phenomena abide for even an instant, and so are empty of permanent abiding and thus of stable existence.
If anything, I think final awakening would be a heightened sense of duality, that results in total lack of ability to any longer conceive of the non-self as being the self, a duality in which you transcend any possibility of mixing up the two things any longer.
Yet, further down at the end of page 157 and continuing to page 158, the Integrated Daniel says:
No-self and True Self are really just two sides of the same coin. There is a great little poem by one Kalu Rinpoche that goes something like:
We live in illusion
And the appearance of things.
There is a reality;
We are that reality.
When you understand this,
You will see that you are nothing.
And, being nothing,
You are everything.
That is all.
Again, this Mahayana way of thinking contradicts MN 22, because if this was true then Buddha is wrong to say to the monks "Therefore, monks, give up whatever is not yours. Your giving it up will for a long time bring you welfare and happiness." And I certainly don't think Buddha is wrong on this! This duality between self and not-self is THE core teaching of Buddha. I don't think a book can rightly be called
Mastering the Core Teachings of the Buddha when it has this one so confused.