this ‘innocent’ remainder of the whole self seems to represent a core of the individual’s imperishable personal spirit — what the ancient Egyptians called the ‘Ba-soul,’ or Alchemy, the winged animating spirit of the transformation process, i.e., Hermes/Mercurius.
Kalsched defines the personal spirit as the imperishable, archetypal core of selfhood, equating it cross-culturally with the Ba-soul, Mercurius, and Winnicott’s True Self, and identifies its violation as the central catastrophe of trauma.
, The Inner World of Trauma: Archetypal Defences of the Personal Spirit, 1996thesis