This is a bit of a repost from something I thought of back in 2004. Someone I was conversing with online, about the nature of existence, posed the question: What is Self?

To me Self is ever-changing, yet constant. It is constant because it is always there, but ever-changing because it is active only within the immediate moment.
In its simplest terms it is who we are, what we think, how we feel at any one given point in time.

Self could be thought of as a faceted jewel with an infinite number of facets, each reflecting what is within and without, spinning to bring new facets
in line as time and circumstance flows on and changes. But as we do not exist in a vacuum, Self is also altered and influenced by everything outside of us. We are in any given moment both individuals and part of a cosmic and complex whole called Creation.

Self is not only what we feel/think internally, but also what we say/do/react to that which is external. Self is changed by the results and effects of our existence upon the entirety of Creation and by the manner in which our interactions are caused to reflect back into us. It is who we are, what we cause, what we give forth and what we take in.

Changing moment by moment.

And in the end Self is the sum total of all those moments strung together as well as the lingering effects on the Universe after we are gone.

Our “Self” continues on after the passing of our physical form. I believe that there are an infinite number of “selves” in existence and an infinite
number of universes. What happens once our physical forms have ceased to be is total conjecture. I believe that we are continually in a process of moving
towards perfection. Perfection of thought, deed, intent and will. I believe that we return to some sort of physical form and that what form we take is determined by how we spent our time in our last form i.e. how our “Self” developed. If we did poorly, left hurt and pain behind as a legacy, did not move towards being a better Self, then we come back as some lesser physical form. One in which we must experience the receiving end of what we left behind previously and what we inflicted on others. That with each step towards our spiritual evolution we will lead a better and more purposeful life. Not to
say that worthy souls will have perfect beautiful bodies and led problem-free  lives. On the contrary, I believe that with each successive “life” we will face
problems, crises and challenges that will test and temper us. They will be instrumental in burning away the “impurities” and weaknesses that keep us from
being the best we possibly can be. Just as fire and tempering are used to purify  iron to make steel and to give it strength.

And what happens when we have reached perfection? When we have evolved as purely as possible? Well then that may be what “Heaven” or Nirvana is. Then we get to devote our energy towards guiding others who are still making the journey.