Not Knowing
Inquiry invites basic knowledge to speak – for instance,
in disclosing the limitations in our knowledge and experience.
It investigates the possibility that knowingness can appear within
what we do not know. Inquiry involves a not-knowing, but it also
involves investigating what you do not know, which allows knowledge
to emerge. In inquiry, there is an interplay between knowing and
not-knowing, but the ground is not-knowing. This ground of not-knowing
is what expresses the necessary openness. And as you investigate,
this openness allows Being to disclose that truth of the situation.
(Spacecruiser Inquiry, pg 100)

We need to remember that basic knowingness is the field of Being
as it manifests in our soul. Inquiry is a dynamic stream that
meanders according to its knowingness of what it does and doesn’t
know as it follows through the field of the soul. This field,
however, exists within a larger field of not-knowing – a
boundless field of mystery and the ground of all of our experience,
perception, and knowledge. (Spacecruiser Inquiry, pg 103)

Knowing, not-knowing
This possibility of not-knowing thoroughly permeates our experience
all the time, in all possibilities and all situations. It is fundamental
to our knowing capacity. In fact, our basic knowing capacity begins
by not-knowing. How can you be knowing, if you don’t first
not know? We tend to be scared of not-knowing; we are unable to
see that it is the pervasive ground of our knowledge. Not-knowing,
in some sense, is where we live all the time. Every piece of knowledge
is situated in not-knowing. It is the space where all knowledge
is. So we can say that basic knowingness is the field of not-knowing,
which can manifest forms within itself that this knowingness recognizes.
(Spacecruiser Inquiry, pg 98)

Understanding and ultimate truth
Well, when I say you can't know it, that doesn't mean you cannot
be it. You can know it as not-knowing. See, we think of knowing
only in terms of concepts. That's why I say you cannot know it,
because you cannot conceptualize it. You can't know it in the
sense that you cannot identify or name it. Your mind cannot look
at it, but your mind knows it's there by the mere fact that when
it approaches absolute reality, the mind disappears. When you
experience absolute reality directly, your mind doesn't know what
happened. In fact the mind is incapable of conceptualizing absolute
reality at all, the mind can't even recall the experience. After
you encounter absolute reality directly, after while your mind
will ask, "What happened? I don't remember what happened!”
And you won't end up with any conceptual knowledge. Why? Because
absolute reality is the experience of unity. The moment the mind
looks at absolute reality, it becomes that reality. The separation
implicit in one thing looking at another dissolves. (Diamond Heart
Book 3, pg 163)