It was common to refer to philosophy itself as a medicine or therapy (therapeia) for the psyche, the soul or mind.
Here’s an interesting article from Donald Robertson (cognitive psychotherapist and author of How to Think Like a Roman Emperor) on Marcus Aurelius, Stoicism and the roots of cognitive behavioural therapy: Marcus Aurelius in Therapy.
As an aside, I’m always struck by the number of lost books – texts mentioned by later writers but lost to modernity…
Indeed, we know that the ancient Stoics, and other philosophers, wrote entire books on the subject of psychopathology and psychotherapy, the cause and cure of emotional problems. One of the most influential was the Therapeutics of Chrysippus, the third head of the Stoic school. Although it’s sadly lost, it’s one of the key influences on a surviving text called On the Diagnosis and Cure of the Soul’s Passions by Galen, the court physician of Marcus Aurelius.
and…
Intriguingly, Marcus adds that Rusticus got him reading certain notes instead about the lectures of Epictetus, “from his own personal collection.” I won’t review the evidence here, but it’s generally agreed this was probably a copy of The Discourses of Epictetus we know today. Of the original eight volumes, though, only four survive — Marcus appears to have also read the missing volumes.
