The Holy Arcana is a new concept to the Tarot, and something which happened purely out of natural flow in the process of developing the Major Arcana for Patch Tarot. Originally, these were intended as four additional Crown cards (also known as the World or Universe cards). You can see then that the Holy Arcana continues the story from the Crown, by progressively zooming out the scene showing the "bigger picture", in the grand scheme of creation.
As Patch Tarot was coming together, I was learning Qabalah and the Tree of Life at the same time, and discovered that there were four hidden places on the Tree of Life that had no cards attributed to them, and so everything connected, and the Holy Arcana became it's own Arcana, with its own mystic meaning.
The Light represents the formless, shapeless, unknowable and undefinable light from which the light of Kether emerges from.
The Truth represents the fundamental Truth which unifies and connects all things in creation, the infinite and boundless from which all things emerge from.
The Way is the nothingness from which even the concept of infinity emerge from, describing that all things come from, and return to nothingness.
The All is tethered to Daath on the tree of life, which represents knowledge - the bridge between idea, and what we call reality.