Having digested the literary works of a contemporary student of Jung (Dr. Robert Aziz), I have pondered this topic a bit lately.
First off, Dr. Aziz exacts a thorough critique of the fact that Jung was way too obsessed with separating "intrapsychic" with "reality", and Aziz offers that this distinction should be trashed in order to truly account for phenomena like "synchronicity." He offers as a simple explanation for this that Jung was in his 70's when he formalized his definition of synchronicity whereas his intrapsychic system of analytical psychology was already well established for 40 years as a "closed-system" model by then, so it was difficult for Jung to come to terms with the real implications of this.
The way I portray this, is I now regard that my mind is not a separated microcosm, but true Flesh and Blood existing here in reality, and as much as I would like to pretend I can shut everything out, the fact is--the neurochemical impulses in my head are influenced to some extent by the stimuli offered by Reality, that is to say, everything happening around me. Albeit the feedback is not always immediate, i.e. it's important to understand there is sometimes a large time lag between the receiving of information from one aspect of the environment and my own tangible actions that could be traced back to such, the influences are there and anyone who prides themselves as being "sensitive" or "in tune" with subtle "energies" of their environment could certainly pat themselves on the back at this point.
The big leap of faith we must make from "conventional mechanistic scientific thinking" to whatever we could call the future thought framework that eventually overtakes humanity as a whole, is the fact that many of these phenomena of "meaning" that we ascribe to being chiefly mental in nature have some abstract basis in Nature and Reality as a whole. That's not to say the rocks falling off cliffs in Grand Canyon National Park have fanciful love lives and some may be accomplished authors of lithographic poetry, but it is to acknowledge that we humans and our brains are subject to the exact same set of physical laws of Reality as the rocks are. In that respect, I judge the human mind not in the dimension of molecule count or energy expenditure or whatever, but in terms of complexity--the world around us ranges in complexity from simple to well beyond what we have comprehended with current scientific inquiry, and our brains are obviously of the latter. So if our brains are so complex, but built of the same material and natural processes as everything else around us, does it not occur to you that other natural processes may proceed with a level of complexity of similar scale? It would make sense to me then, that what we see as "meaning" in our observations could have analogous presence in other natural events or processes. The key here is, this doesn't mean everything magical truly exists, it just means there is probably a framework of abstract meaning that could account for such thoughts--e.g. the "idea" of time travel itself could be considered as an idea manifestation of our desire to control, since what would be the point of time travel except to either control the flow of Reality or to satisfy our own desire for information to control our own destiny? That time travel doesn't really exist (to the best and most practical, occam's razor approved explanation we have thus far), tells us that this innate desire for control is bullshit in the first place.
The concept of "meaning" I think Jung tried to ascribe in the concept of the "archetype", calling them "transpersonal" "collective unconscious" or whatever mystical sounding terms he used--the fact is, "archetype" is to "meaning" as "motif" or "pattern" is to physical form. Like the idea of a fold or crease--the basic idea of a fold or crease is found in many different places, the corner of a rectilinear wall, the crease of a book, the crease formed inside my elbow when I bend my arm, etc. is a basic idea that has "transpersonal" presence and probably has existed as long as the Universe existed, but we don't go around worshiping every crease we find as if it were some sort of God. Likewise, there are tokens of "meaning"--like the Hero archetype, the idea of something coming through and "making right" something that is proceeding in a direction of disintegration or destruction--that have everyday occurrences not just in matters of humanity, but in the physical realm as well... It's awfully easy to sign this off as just being "all in our head," but I think there's more to be learned by stepping outside of that paradigm of thought.
Anyway, Jung did basically say that Synchronicity is founded in the archetype, that archetypes are the content of synchronistic phenomena, but his description of it is derived from the paradigmatic standpoint of it being "all in our head" to some extent, and that archetypes are "meaning" that is all in our head. Aziz would have you take the leap otherwise and understand it's no accident that synchronistic phenomena are based in Reality outside of our heads. That's not to mean that we actually know what we're talking about or have truly identified the legitimate meaning of synchronistic phenomena, it's to say that if we learned and studied it in depth we could derive meaning from it, indeed we may even acknowledge our personal role in the whole event's emergence, and it would be important for us to understand what could come out of that. Ultimately what we do *with* synchronistic thoughts and phenomena is the only real reason why we'd want to discuss them.
I think at the end of the century, or maybe the next, or who knows when, we humans will have resolved many of the great questions of what people ascribe to "mysticism" as being rather ordinary phenomena in the same way that we regard much elementary mathematics and physics as being rather ordinary, when it was probably awe-inspiring and groundbreaking in the days of which much of the mathematics we learn in grade school was conceived.
But one thing is damned certain, we can't IGNORE these phenomena outright; they are NOT going away. Ponder that in your pipe and smoke it ;-)