On the Tarot of Marseille card by Jacques Viéville (right), the Filius Philosophorum, or Sun Child, is sitting on a horse. This symbolizes overcoming the emotions and animal drives; an important aspect of the Magnum Opus, that one might regard as part of the purification process.
The banner is an element that expresses victory. The two different colors of the banner refer to the fusion of duality, just like the red cross on the horse’s hindquarters. On Nicolas Bodet’s card (bottom right), a derivative of Jacques Viéville’s card, the banner itself has a cross.
Certainly at that time, a banner with a cross was associated with the resurrection of Christ. On the symbolic level, the Bible story of Jesus rising from the dead is about a spiritual rebirth.
Read more about the symbolism in the Bible in my book “Mary Magdalene, the disciple whom Jesus loved.”
The Filius Philosophorum, or SUN CHILD, is sitting on a HOBBY HORSE; symbol for mastery over the emotions and animal drives. The boy carries the BANNER the resurrected Christ is depicted with in iconografy, which stands for victory over (spiritual) death. The WALL communicates that we get a view into the interior of the alchemist. Around the wall are personifications of the PLANETS. These represent the SEVEN CHAKRAS that have been purified and activated. The angel with Bible refers to DIVINE WISDOM = Sophia = the kundalini energy. (Traité d’Astrologie, Johannes Hartlieb, circa 1540)