The concept of The Three Cauldrons is used far less that the Seven Chakras but this is used within the Ar-Kan Rune-Lag System so I feel that it needs some more attention. In fact the three centres which stand upon the Spinal Column are the Three Centres of Human Consciousness -
Head-Centre (Odroerir - Ansuz) - This is the Centre of Intelligence, since we use the terms 'use your head', 'he's lost his head', or 'he's got his head screwed on' and other terms suggesting intelligence.
Heart-Centre (Son - Lagu) - This is the Centre of the Emotions since we use the terms 'with all my heart', 'he put his heart and soul into the work', 'his heart was not in the job', or 'a heart to heart discussion' etc.
Base-Centre (Bodn - Ur) - The Centre of the Instincts since we say 'he had a gut feeling', or 'he's got guts'. This centre is thus that of the human instincts, but it is also a centre of will and strength.
A Chinese Scientist who works with acupuncture has proven (it seems) that there is a link between the brain and the gut, and that the gut does have 'consciousness, and indeed acts as a 'brain'. What this acupuncturist did was to use points on the gut area and after doing so did an MRS Scan on the patient and this showed up as changes in the nerves in the brain. I believe that some scientists have also looked at consciousness in the heart too. So what is said here is not just conjecture.
The squirrel, Ratatosk, runs up and down the World Tree, as does the runic formula run up and down - ALU-ULA. The base centre - Bodn - can mean 'Earth' (boden is 'earth' in German); but there is another meaning we can get from Old English -
boedan - to proclaim,
bodian - to announce,
boda - messenger.
Ratatosk is the 'messenger' that runs up and down the World Tree between the Eagle at the top and the Serpent at the bottom.
The Rad-Rune has a 'column' (I) which represents the Spinal Column in Man; the reverse Sig-Rune is the Fire-Serpent which moves upwards along the Spinal Column. This is the ascending Current of Energy - the Igneous Fire. The Rad-Rune is thus Rata-tosk which is the ascending-descending energy associated with the Fire-Serpent.
It would seem obvious that the Base-Centre - UR - is the 'Primal Centre' or the 'Source'. This is the Hara-Centre which stands at the centre of the human body, and thus the 'Point of Balance'. This area contains the Manipura Chakra which is associated with Ingwe (Agni), the Swastika (Force of Fire), the Ram, and the mantra 'RAM'. Below this is the 'Water-Centre', whence Ingwe arises - the Absu - thus 'Fire-from-Water'. The Fire-Serpent lies dormant in the waters below the World Column. The Ur-Rune is also connected to the concept of 'our' and thus to the idea of 'vast' and 'infinite'.
The Sanskrit rasa means 'vital essence' and rasayana means 'Elexir of Life'; these are the Life-Force associated with the 'Sap' in plants and the 'Blood' in Man. Here we can see the link to the Ing-Rune because Ingwe is the 'Sap of the Plants' and also the 'Blood of Man', and the Ing-Rune is the 'Rune of the Blood'.
The use of the Formula ALU-ULA suggests that this Magical Force (which is what this is) works in two different worlds simultaneously, or two different dimensions if you like a modern term. Of course, the AEsc-Rune is the Ancestral Rune, and the Os-Rune is the Rune of the Ancestral God (Woden), so we can also use the alternative OLU-ULO Formula which invokes the Ancestral God rather than the Ancestral Spirits.