We have then to describe and to explain a building, the upper storey of which was erected in the nineteenth century, the ground floor dates from the sixteenth century, and a careful examination of the masonry discloses the fact that it was reconstructed from a dwelling-tower of the eleventh century. In the cellar we discover Roman foundation walls, and under the cellar a filled-in cave, in the floor of which stone tools are found, and remnants of glacial fauna in the layers below. That would be a sort of picture of our own mental structures. We live in the upper storey, and are only dimly aware that our lower storey is somewhat old-fashioned. As to what lies beneath the superficial crust of the earth we remain quite unconscious
So far so good. I can go along with this, it's a neat formulation. I'm not totally convinced, particularly when it comes to the glacial fauna which, it seems to me, is stretching the history of the 'building' to an extreme in order to create a link to the unknown, or unconscious. But okay, let's go on.
But the deeper we descend into the past the narrower the horizon becomes, and in the darkness we come upon the nearest and most intimate things, till finally we reach the naked rock floor, down to that early dawn of time when reindeer hunters fought for a bare and wretched existence against the elemental forms of wild nature. These men were still in the full possession of their animal instincts, without which their existence would have been impossible. The free sway of the instincts is not consistent with a powerful and comprehensive consciousness. The consciousness of primitives, as of the child, is of a spasmodic nature; his world too, like the child's, is very limited. Our childhood even rehearses, according to the phylogenetic principle, reminiscences of the pre-history of the race and of mankind in general. Phylogenetically as well as ontogenetically we have grown up out of the dark confines of the earth.
This is where, it seems to me, Jung descends into babbling. There is positively no proof that early man's consciousness was 'spasmodic', and his world is only limited to the extent that physically it was confined to where he could walk. The leap from that to the suggestion that his entire world - physical but also mental - is limited is unsustainable.
And thus the whole analogy begins to fall into discredit. I can certainly see that an individual's beliefs, ideals, memories can be seen as settling within him like some sort of archaeological layering, and it could then be theoretically possible to slice through it to see the genesis of those beliefs. I will even allow that some of this is undoubtedly subconscious or unconscious. But to go back to the naked rock floor, not only of my existence but of mankind itself, and try to extrapolate from this general mass something that is useful about my personal state, is a futile pastime.