While the fundamental truth never changes: what non-duality points to—the ones difficult to name, impossible to conceptualize, and more directly known than any "thing" else—since are Are that, this unnamable awareness, consciousness, or presence, whatever you want to call it; whilst That never changes, the words, the expressions and the human understanding can and do continually change and (hopefully) evolve, as can the living of it.
And, every teacher, writer or student of Truth is a living expression, with a unique perspective, a unique combination of nature and nurture, a path through apparent time and space, yet grounded and rooted in the same unnamable Reality (there can only be one, remember? Even if we can't pin it down, grasp, own or control it!... ).
Call the "principles" or fundamental truths the "facts of life" , but facts of life about our subjective nature – that realm, so to speak, which, given it's fundamental nature, is similar to quantum mechanics in being paradoxical.
"The natural state" is one way of framing this paradox: if it's natural, then how can we ever not be in the natural state? This parallels the paradox about "being in the moment" or "in the Now"; If the present, the now, is all that exists—and indeed a real past or future is arguably and rightly so, purely theoretical or speculative, and not a fundamental aspect of reality—in other words, time and space are just a mental construct when an apparent "me" pops into apparent existence in subjective experience (which is all there is, really, when you get right down tto it, honestly)—not a priori ground of reality—and this apparent body, mind and world arise from the ineffable Source every moment—then how can one be out of it? In other words, it's obviously impossible to ever not be in the totality of every moment, experientially speaking, in what Is. You can't be outside of everything and all that is now. There is no "other", really, in absolute subjectivity – what's been called "pure consciousness", or "consciousness without an object".
Phew. But that's a tough order, a tall order – a requirement we can't seem to meet. How many of is are like Ramana Maharshi (the "great" Indian sage), or Atmananda Krishna Menon (the sage of Direct Path fame), or Buddha or Christ? We can't seem to measure up to the past images, these models of supposed spiritual perfection.
But, back to the moment, haha. How the heck do we get out of the moment, if it's all there is? How do we get out of the Now (as in, The Power of Now, Eckarte Tolle's famous book)? Descriptively, this out-of-the moment sense, this state, is said and felt like one is "in the mind" or "in the head" or "preoccupied" – namely, if you look at the content of this preoccupation, with past and future. Isn't every worry about the future, and isn't every rumination, resentment, regret (notice the "re-") about the past or future?
And there we are (or here we are) as a result, trying to get back to the present, the now, that is already all there Is. What fun, what craziness! How is this even possible – this charade of Being? How do we manage to torture ourselves with illusions, with imagination? What powers we have, apparently!
We also, of course, deliberately try and escape the present—if we find it unpleasant or intolerable, uncomfortable or infuriating, whatever—or simply want to entertain ourselves—by various means. Videos, projects, chatting with friends, work, drugs, alcohol, sleeping, sex, intense partying or activities like car racing or sports... But, here we are, still in the moment, in the midst, and at the end of it all – the one we never managed to really escape from. Indeed we seem to often want to avoid what we see as scary or bad; we want relief from what ails us inside or outside (really, it's all "inside", if you are honest with yourself about experience). This seems to be universal to the human condition.
Thus it is interesting that one spiritual teacher described Self Realization or “awakwning” as "the absence of a tendency of avoidance", haha. He also seemed to say that there's nothing you can do—as a seemingly separate entity—to avoid, or get out of it. And he would jokingly mock the seekers with "What to do?" (I am speaking of Karl Renz).
Indeed, what to do?
Sometimes, nothing.
Sometimes, less is more.