Mer refers to a specific kind of light that was understood in Egypt during the 18th Dynasty following the reorientation of religions toward the worship of a one God of all creation. "Mer" was seen as two counter-rotating fields of light spinning in the same space. These fields are generated when a person performs specific breathing patterns.
Ka refers to the individual spirit of a person.
Ba refers to the spirit's interpretation of its particular reality. In the human reality, Ba is usually defined as the body or physical reality. In other realities where spirits don't have bodies, Ba refers to their concepts or interpretation of reality in the realm in which they exist.
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