Trees, shrubs, grass and 10% ethanol petrol pumps are green.
These things are what the brown earth makes possible and makes some people weak at the knees with the desire to be frugal and protective.
Green is the colour of nature.
Sayings in The Green Series are about biology and conservation, about the rare and threatened, and the trees, and emissions, and sometimes the people who would love all these things.
It is not clear to me as the chronicler of Confused Confucius if the Confused One is a greenie or not. There are hints of tree-hugging and koala selfies and yet this could be the dry wit that soars above our heads.
I will leave it to you to decide.