Well, I’ve come down from my mountain and here’s my initial thoughts:
What does it take to change one’s essence? I think one’s essence is just what one is–at the core–and since I personally believe nothing is permanent, that things are always changing, it only makes sense to talk about one’s essence in the moment. However, it would also be fair to say that the change we undergo may be so gradual that we can get away with talking about our essence over an extended period of time. There is also the fact of recurrence, which I spoke about before, which is the idea that our essence–the core of our being–is not something constant but something that keeps recurring–personal tastes, memories, my image in the mirror, hearing my name–all these go towards my self-concept and my essence because they keep repeating for me, and maybe we can talk about our essence as the general “flavor” that all these recurring experiences or states mix together to become–like the “essence” of a pixel flashing on a screen between red and yellow might be “orange”.
But I always like to argue from a subjectivist point of view–I like to trace the things in our world back to first person experience. If we indeed have an “essence”, I trace that back to concepts–self-concepts, self-identities–how we define ourselves, as I pointed out earlier. I can understand Arc’s point that if we’re talking about self-definitions, we’re talking about something that seems to be on the surface–how we think of ourselves on a conscious level–and one’s true essence must be something deep within the core of our being. But I disagree that thought and the definitions we give to things (including ourselves) is at the surface; I think our minds are the core of our being–including all our thoughts, all our emotions, all our memories, all our desires, all our pains and pleasures. It is the source from which thoughts and the definitions we give to things spring. We imbue things, including ourselves, with whatever definitions we give them, and this for us constitutes their essence. I’m opposed to the idea that the core of a thing, its fundamental identity, is always necessarily hidden. We are our own core, and the proof of this is precisely that we are exposed to ourselves.
But my subjectivist views are not the only views out there. If you’re a strict Platonist, for example, you would say that one’s essence isn’t just reduced to one’s self-definition. An “essence” to a Platonist is just as real, just as objective, and just as independent of human thought as are rocks, shoes, and tin cans–only they don’t subsist as physical bodies, but rather the “metaphysical” or “spiritual” identity of things, the abstract identity of things that we see with our minds, not with our senses. An essence is whatever it is that resides within a thing to give that thing its identity–what makes a chair a chair, what makes a house a house, what makes my phone my phone. This supposedly doesn’t change just by my re-thinking it. My phone doesn’t cease to be my phone just by my redefining it. And so too with the self.
^ I’ve never really been a strong adherent to Platonism, but I can’t really account for where I’m coming from unless I also explain things from opposing points of view. Sometimes a bit of contrast makes the things being contrasted more clear.