Everything in our experience is comprised of borders. Each and every thing
begins at a certain point and only extends as far as its margins will
allow. That's why I'm not you and you're not me. For I begin here
while you begin there, and if I went on from my here to your
there, you and I would meld, we'd each lose definition, and many
things about us would start to get vague.
I'd wonder, for example, if it was I who was feeling happy or you; if my
sneezing deserved your gesuntheit, or if you were getting a cold,
and so forth. It goes further yet, though. Would my childhood memories be
partly yours, or are they all my own, with you there as a constant
observer? Would you have to come along as a matter of course if I decided
to travel, etc.?
It touches on many other things in our experience, too, including our
senses. We'd really be thrown if our ability to hear somehow or another
combined with our ability to see for example. Or if we managed to smell
things as we touched them. The point of the matter is that all of that is
out of our experience since it's outside the realm of this physical world.
(Nonetheless see Exodus 20:15, where we're told that "all the people
saw the thunder ... and the sound of the Shofar" when the Torah was
revealed at Mount Sinai, which only comes to underscore the supernatural
nature of the event.)
Nevertheless, understand that without borders there'd be no sense or
reason in the world; we simply wouldn't know what's what. And so it's safe
to say that borders help mold our beings, define our life, and form the
basis of the physical world.
Yet there are phenomena that don't have set borders; that are beyond the
confines of space and time, physicality, and definition. They inhabit the
spiritual realm. And it has a reality of its own.