The first two questions in the Byron Katie inquiries are Is it true? and Can I absolutely know that it is true?
Few beliefs questioned
In the beginning, it may seem that most of our beliefs are true. I believe in it, so it naturally appears true to me.
Personal beliefs questioned
Then, we may go through a phase where certain beliefs are seen as clearly not true, such as my personal opinions. And others are still unquestioned and appear true, such as the ones taken as given in our culture, or by most humans anywhere.
Any belief questioned
Finally, we may realize that any belief is questionable. When sincerely explored, any belief falls apart – it is shown to not accurately reflect our immediate experience. And this goes for even those beliefs taken for granted by most humans – such as I am a man or woman, I am an adult or child, I am a human being, there is I and Other, I experience, something exists, and so on.
This is where Big Mind opens up for us, where we begin to taste the Ground. The most basic identities start to fall away, such as that of a man or woman, a human being, or awareness. The most core beliefs, such as in the idea of I, now seem precarious and begin to erode.