In his commentary on the Third Branch of the Mabinogion, JMG states that the four main characters are actually aspects of one person.
- Cigfa (“House of Flesh”) is the Body.
- Pryderi is the Soul.
- Rhiannon is the Spirit.
- Manawyddan is the Mind.
When Pryderi and Rhiannon are both trapped by the gold bowl, it reminded me of The Book of Lambspring, when the Soul and the Spirit leave the Body. (And this is also reminiscent of the third marriage in alchemy, after which the united Soul and Spirit return to the Body.)
I reviewed the Third Branch to see if this aligned with the other aspects of the story.
First, the characters made saddles. Saddles are used to ride horses… seems to hearken back to Rhiannon as Epona in the First Branch.
Second, the characters made shields. Shields, conflict… seems to fit all the fighting in the Second Branch.
Third, the characters made shoes. Shoes connect (or mediate?) our relationship with the Earth. Pryderi married Cigfa (Physical Body, so Earth) in the First Branch, but at the very end. His adventures with Cigfa were described in the Third Branch.
Then, Pryderi encountered a pure white boar, a symbol of the entrance to the Otherworld. And following that boar led him to the gold bowl.
Now why a gold bowl? Gold is associated with the Divine, as are circles (and bowls tend to be circular). An Internet search revealed that the gold bowl in the Third Branch possibly referred to the Caergwrle Bowl. This bowl (made of shale, tin, and gold) depicts a solar boat (a precursor to the solar chariot) decorated with waves, oars, shields, and eyes which together represent a magical or divine journey.
So the Soul and Spirit went on a Divine Journey… they completed the third alchemical marriage and then the Mind brought them back to the Body!
On their journey, Manawyddan was a gate and Rhiannon was a horse (technically, the author of the Third Branch used a different term, but since it has already been established that Rhiannon is related to Epona, referring to her as a horse seems more respectful). Or, the Soul chooses to go to the Divine (the gate can be opened or closed) and the Spirit is how the Soul travels to the Divine.
Since Gorsedd Arberth is the Portal of Initiation, all of this seems to fit well.