[larkery]

I think it would be remarkably weird if the state inside me were entirely uncoupled from 'exterior things'.

In the zen view, the 'trick' is that there are no exterior things because the distinction between the exterior and interior is artificial. Processes of change may reach across that boundary just as they cross any other boundary we care to draw, so there is no absolutely self-governed component.

Assuming (perhaps wrongly, let me know if I'm overreaching) that you see your self as a stoic or happy to interpret them, what do you think the Aurelius quote above means? What is the soul which it's talking about?

We can identify patterns that remain stable for a bit, so you might say that my soul is whatever essential features or patterns remain unchanged, but on the long span I find it hard to imagine such features. After all I will be eaten by worms or incinerated sooner or later.