In modern magic theory, the human soul typically represents the spirit. All resonance with elemental particles, the pulling of arcane factors, and the construction of magical circles rely on mental power as the brushstroke.
As for the physical body, many mages consider it the vessel that carries the soul, the foundation allowing human mental power to persist in the world, a unity of matter and energy.
After all, even undead creatures require specific mediums to move, such as bones or other objects that once had a prolonged connection with the body. This is exactly how ghostly tales of haunted castles came into existence.
In reality, when the physical body undergoes intense tremors, the soul momentarily becomes disoriented as well, unable to immediately use mental power to attract elemental particles and sketch magical circles.
