When I was in my mid-teens there were a couple of shifts.
First, I was identified as this human self.
Then, there was a shift in the “center of gravity” of what I experienced myself as. I found myself observing while what was observed seemed very distant. This human self with all its experiences and the wider world seemed far away. My experience was that something was seriously wrong, and several specialists could find no explanation.
After almost exactly a year, there was another shift, this time into oneness. All was revealed as God. This universe and this human being with all its experiences is the divine taking this form and the experiences and experiencing it all. Any sense of being a separate self is the divine having that experience for itself, locally and temporarily, and there is no ultimate reality to it.
As a human being, I did nothing for this to happen, it came out of the blue.
And in hindsight, the shift into observing and then oneness makes sense.
First, there is the usual separation consciousness. Then, an intermediate shift where “I” was the one observing and experiences all the experiences. As Adya says, it’s a simple and clean duality of observer and observed. And then, a shift into oneness. In hindsight, the observer-observed shift seems like a stepping stone, a way into oneness.
Since then, it’s been a journey of clarification, deepening, rediscovering, and learning to live from it. And the process has sometimes been far more messy than that sentence makes it sound like!
Why did these shifts happen? I don’t really know. Some would say it has to do with spiritual practices in past lives. I would also guess it happened partly because of the teenage angst I experienced at the time. It was difficult to be this human self, so something in me shifted into what I am. Something in me knew how to shift.