Stilpo is an interesting character. A Megarian, and one of the tutors of Zeno of Citium before he founded the Stoa, Stilpo reportedly witnessed the razing of his country, loss of his people and family, and walked out of the ashy remains with a smile, has he ‘had all his goods with him.’
Megarians were interested in Logic and Virtue, which Zeno and Stoicism inherits. I don’t recall that we hear of Stilpo other than this little quip in Seneca.
The Stoic’s ‘self-sufficiency’ and ability to retire into himself (which Marcus will refer to as ‘the Inner Citadel) seems to be the method for mixing with the world, yet not being affected by it.
I need to think on this some more. If we had inherited a holistic program from the old Stoics, I’d suspect we’d learn about some specific meditation techinques around this time, yet sadly, those Letters, dear Seneca, seem to have been lost in the post of time.