The Holy Grail has long been revered in Art as a symbol of the divine feminine. Inspired by the Mythic Tarot, it invokes the Magus card, moment the Magician becomes empowered & picks up the 4 magical elemental tools, the sword, wand, pentacle & grail, & realises he/she is master of their destiny.
Essentially it's about the process of creation itself from spirit into matter. The fire of the star of Venus is the inspiration of spirit, shoots down in lightning to the Magi, he breaths in the air (mind ), & she breaths the water ( emotions ) into the sword and the grail, then they plant the seed of manifestation, the pentacle in the earth, which grows in a tree… then bursting forth flowers in a cycle of manifestation. It could also be the lovers card… the Beltane dance of masculine & feminine within the weave of the caduceus, or the two figures could describe the hermaphrodite in the world card, symbolising wholeness, completion of a soul and the hero’s journey.
(http://emanations.co.uk/art/the-magis-grail/)