He wasn't content to sit and watch, ... (Para. 9)
Meaning: He wasn't happy or satisfied just by sitting and watching.
The adjective "content" is often used with a with-phrase or followed by an infinitive phrase:
I am not content with beautiful dreams: I want beautiful realities. 我不满足于美丽的梦想, 我要的是美丽的现实。
He's perfectly content to live in a simple room and to paint pictures all day. 身居陋室, 整日作画, 他对此已完全心满意足了。