I recall Herwig once mentioning that any organ can hold any emotion for us, but that they tend to have a predilection for certain varieties: lungs for grief, livers for anger, kidneys for relationship issues, and so on. In 1976, after a number of years working as a Religious Science practitioner, Louise Hay (1926-2017) published an alphabetical list of the metaphysical causes of illnesses she’d been encountering. If you’re ever intellectually curious about the backstory of an emotion you healed during a session, chances are Louise has your answer! (“Intellectually curious” because the healing has, of course, already occurred.)
Hay House, the publishing firm Louis founded in 1984, still sells “Heal Your Body”, which has since been updated as “You Can Heal Your Life”, both a book and a film. (A quick google will also bring up a few sites that post the A-Z list.) Thanks, Louise!