What's that?

It might all be true, but I don't think it highly probable. In the early 20th Century when Guglielmo Marconi and his contemporaries were exploring how intelligence could be transmitted and received, apparently through an invisible "ether," spiritualists saw a new hope that the "spirits" they believed in, or pretended to, might also be able to communicate with us through some "ether beyond."

Nope. I don't think so. I think a highly evolved and richly complex biological system is necessary.

Here's a conjecture. How about looking at a "spirit" as if it were a system of memes, like a richly complex software program that can run "on" or "in" a biological brain/mind? If a living mind is needed to sustain consciousness (much as one might long to believe consciousness could exist and travel separately, and communicate), then that, the former, is a kind of "spirit" I could accept a belief in. Hey, even if it means that that "I" I mentioned is only an illusory side-effect of such an immenseley complex meme.

So, picture the mind "running" a highly-evolved meme much the way a central processor can run a carefully developed, deeply complex, humongous program or system of programs. In the conjecture, that's what these big brains do. (Is it conceited of us to believe other animals might not also develop their own rich memes, over millions of generations using larger, or even more compact brains? Maybe we shouldn't dismiss that unproven negative.) You might even look at DNA as a built-in part (a nature "spirit"?) Where would you draw the line? Adaptation in a complex environment would contribute a more volatile part. Kids learn meme systems from their families and societies, and disciples learn meme systems from their teachers.

By the way, I think it makes sense to honor the dead by adopting some of their cherished memes, their attitudes, some of the ways they would act when they were alive. Then one really can preserve and enliven an honored "spirit" (understood as a system of memes), and even contribute refinements, gently adapting it to better fit current and future circumstance.

Likewise, when you and I die, will we have created enough of an impact to not only be remembered, but that some of the memes we have reinforced or refined a little, or even invented over the course of our lives, be adopted and brought to new life? I think it probable, but the extent to which they are adopted will depend on many factors.

We can, with little thought, identify some thousand-year-old memes; look at the religions; look at the Japanese Tea Ceremony chanoyu. I wonder, can we identify any million-year-old memes that are still alive and well today? Like the "art" of tending a nice fire? (I think some of these conjectures might serve as targets for genuine scientific inquiry in the field of Human phDevelopment.)

But is not the "real" spirit the inner self, the profound and quenching Presence of being? The consciousness itself? Or (or and), are "inner-self" and "other" only illusions fabricated by the way our brains work? Well, yes. And also no, given the need to step away from mental constructs and just be. I guess about now a good roshi would tell me to shut up and notice, once in a while, what the phrase "non-duality" points to.

Nonetheless...

The ancient Indian way is an informative subject to consider: where a person grows old enough, and finishes enough with all the demands and responsibilities of living and raising family, that s/he may then have the means to retire the prominence of the "ego," the "mechanical" mental apparatus, in such a way that frees her from all the constant entanglements of the thinking mind. That sets the stage for further growth of natural spirituality to proceed over the remaining years, for example along the Indian eight-fold path, perhaps to flower and to set seed.

But I'm not saying one needs to become an old renunciate in the forests of India to realize enlightenment. This understanding of "spirit" is as natural a "thing" as mathematics: it has the ability to arise independently of any particular thought-system of any given time and place. An educated middle way is today not different in substance and result from those revered in ancient India, or in the Middle East, or in Native America.