This may seem a bit mystical, and I'm not - so it isn't, really.
On a recent birthday I recalled a thought I'd had when much younger, when I wondered if I would be much different as a person if I'd been born another day. The main difference might be one that perhaps provides a shadow of a rationale for the personality predictions of astrology: I'd have spent my first months of life in a different season, and one might imagine that this could color one's view of the world. My first six months or so were spent during the cold and dreary months of the year - perhaps I'd be slightly different if it were Spring and Summer instead.
That isn't really what I was after, though; I thought it might be an interesting exercise in imagination to toss away personal details, and see how much of "me" was left as I went along. Would I be the same person if I'd been given a different name? I think so, without a lot of doubt, though having a "B" at the beginning of my last name got me through lots of institutional processes faster than I would have been had my last name been "Zuppa" or "Zabaglione". So there might have been some small difference, but I don't think it'd have been significant.
It's an interesting exercise to try - what if you'd been born in a different country? What if you'd been born in a different century? How much of your personality, your "soul" if you wish to consider it in those terms, would be the same, and how much would be different?
My view is that I'd be the same person, though my different experiences might have led to different choices in life. I can't get away from the sense of having a central identity that wouldn't be subject to the vicissitudes of time and place.
A recent TED talk (Technology, Entertainment, Design; www.ted.com) by Steven Pinker, "Chalking it up to the blank slate" (just under 23 minutes long; well worth the time) addresses this from a neuroscience point of view. The evidence he cites for surprisingly similar behavior from identical twins, even raised in different environments, he uses to point to the importance of underlying brain structure as a determiner for human nature. Even twins aren't *exactly* the same - and if one of us were born in another place and time, physically identical to who we were at birth, we'd be even more similar to our current selves than twins are, despite environmental differences..
Then I began to wonder: who in the past might have shared some or all of the elements that make up that identity? It really doesn't matter if you get to be the way you are via nature or nurture - what you are in terms of outlook, personality, affinities, and so forth may have existed before, and may exist again at some time in the future, in whole or in part. I don't know quite what to call this: perhaps 'accidental reincarnation". It doesn't require any mysticism to consider it a possibility.
Perhaps this has happened to you: you'll be reading some bit of history, before you turn the page you think that if you were there/then, you'd say something specific, or react in some way - and you turn the page, and find that the person said or did just that. Now in the obvious cases this isn't so striking - if nearly anyone would have said or done it. But what about when almost no one would have? It can be a very eerie experience, the sense that some part of your mental life existed before you were born.
A few years after this idea had occurred to me (this was in the 1970's), I stumbled on a poem of Jorge Luis Borges. It's not his best, but the fact that it touches on the same point was a bit of a surprise:
Inscription On Any Tomb
Let not the rash marble risk
garrulous breaches of oblivion's omnipotence,
in many worlds recalling
name, renown, events, birthplace.
All those glass jewels are best left in the dark.
Let not the marble say what men do not.
The essentials of the dead man's life -
the trembling hope,
the implacable miracle of pain, the wonder of sensual delight -
will abide forever.
Blindly the willful soul asks for length of days
when its survival is assured by the lives of others,
when you yourself are the embodied continuance
of those who did not live into your time
and others will be (and are) your immortality on earth.
Perhaps my surprise when reading this was that it almost proves the point: while wondering if there were others in the past who'd thought similar thoughts to my own, I'd found someone else thinking the same thing!
The "(and are)" part in the last line hadn't occurred to me (and I must admit this whole topic was something of a passing thought). It's not just that there may have been people in the past (and may be in the future) who to a lesser or greater extent were "me", but that this may be true of others alive now. And of course it's not that they're identically me; they may just have some overlap in attitude, imagination, instinct, emotional response, world view, sense of humor, or any of the other aspects that make up the mental life of an individual.
Maybe we do intuitively understand these kinds of mental life overlaps; when reading history, or even watching a movie, we identify with some characters, and can at least appreciate the actions of others, even if we wouldn't act like they did. If we couldn't do this, there'd be little value in history or literature. To the extent that I understand Christian thinking about the brotherhood of man, I make sense of it this way: we each share a little bit of each other.
One can take this further - Terence (Publius Terentius Afer, 185 BC - 159 BC) said "Homo sum: humani nil a me alienum puto " (I am a man: nothing human is alien to me). When I first read this I thought it to be quite powerful, but over time I've come to doubt it: when I read of certain types of crimes, too bizarre or disgusting to mention here, I feel I'm touching something alien. On the other hand, these human actions may just reflect mental illness. Or perhaps we define something as mental illness precisely when we can't empathize with it at all.
The type of overlap of mental outlook I'm speaking of might even cross species boundaries, though probably with some inherent limits. Anyone who has spent time around dogs knows they have distinct individual personalities, and, even ignoring the anthropomorphism we sometimes bring to such observations, one may find traits that humans share. I wonder how far one might take this - say, if the mind of a dinosaur that walked her 70 million years ago, perceiving similar landscapes, may have had some overlap with how I see the world. It may be that such similarities are an inevitable hallmark of consciousness.
I found another poem recently, unpublished for some time, this one by Cavafy. He's perhaps most famous for Waiting for the Barbarians, but others of my favorites are Ithaca and Thermopylae (if you've never read them they are worth the web detour). While this may have more to do with the specifics of Cavafy's life, it still touches on the same theme:
HiddenSo I'll die, my specific memories vanish, but some day, maybe many days, a new person will be born who will more or less, in many combinations, be me.
From all I've done and all I've said
let them not seek to find who I've been.
An obstacle stood and transformed
my acts and way of my life.
An obstacle stood and stopped me
many a time as I was going to speak.
My most unobserved acts,
and my writings the most covered -
thence only they will feel me.
But mayhaps it is not worth to spend
this much care and this much effort to know me.
For - in the more perfect society -
someone else like me created
will certainly appear and freely act.