The concept of a tiered cosmos is important for an understanding of the meaning of megalithic structures. The Greek word cosmos is not just another term of what we today call the universe. Moreover it refers to the sum of experiences of a society. That includes the physical world, but also religious concepts. An important feature of most (if not all) religions is a tiered cosmos: Many cultures know separate realms for the death and living. The realm for the dead is quite often called the nether world or underworld and the realm for the living the upper world.

Lewis-Williams and Pearce [1] argue that many cultures developed models of a tiered cosmos that have many aspects in common. It seems very likely that these models emerged independently from each other since the cultures that developed them were separated geographically and in time. Examples include cultures in South America to Siberia or Asia and all these cultures know a tiered cosmos. Lewis-Williams and Pearce conclude that this is the case because human beings are physically very similar (we all have the same biology). Therefore there must be a physical or better neurological reason that explains why many cultures come up with similar models of the cosmos. They go further on arguing that Neolithic man was physically not much different from present man and therefore we can assume (with some care) Neolithic people had the same neurological experiences than we have today.

Altered stages of consciousness can be induced by many means: including excessive fasting, drumming, dancing, near death experience and psychoactive drugs. Individuals that experienced a change in their state of consciousness report several phenomena that can be grouped into patterns. Lewis-Williams and Dowson [2] identified three stages of altered consciousness that a person ideally experiences (this is not necessary the case). During this course or trip certain geometrical patterns are intrinsically generated by the visual system (even with closed eye). These effects are known as entoptic phenomena.

Three stages of altered consciousness (after Lewis-Williams&Pearce).

Altered stages of consciousness are also very often accompanied by the experience of being decoupled from the body and flight. In shamanistic rituals this is often interpreted as a transit from the real to a spiritual world.

The passage through the vortex between stage 2 + 3 is also a subject commonly found in many religious believes: Flying or walking through a funnel.

Altered stages of consciousness play a central role in many shamanic cultures. The shamans or ritual specialists are intentionally changing their state of consciousness to transit into another realm of their cosmos. Lewis-Williams and Pearce [1] suggest that the experience of these transitions is the reason why so many different cultures have a model of a tiered cosmos.

@Book{lewis2005inside,
title = {{I}nside the {N}eolithic mind: consciousness, cosmos and the realm of the gods},
publisher = {Thames \& Hudson},
year = {2005},
author = {Lewis-Williams, David and Pearce, David},
}

@Article{Lewis-Williams1988,
author = {David Lewis-Williams and T.A. Dowson},
title = {The signs of all times: entoptic phenomena in {U}pper {P}aleolithic art},
journal = {Antiquity},
year = {1988},
volume = {29},
pages = {201--45},
}