Full Idea
Zeno of Citium wrote a (lost) book entitled 'That Which is Appropriate'.
Gist of Idea
One of Zeno's books was 'That Which is Appropriate'
Source
report of Zeno (Citium) (fragments/reports [c.294 BCE]) by A.A. Long - Hellenistic Philosophy 4.1
A Reaction
I cite this because I take it to be about what in Aristotle called 'the mean' - to emphasise that the mean is not what is average, or midway between the extremes, but what is a balanced response to each situation
Book Reference
Long,A.A.: 'Hellenistic Philosophy' [Duckworth 1986], p.113