People
Look within. Within is the fountain of good, and it will ever bubble up, if thou wilt ever dig.
— Marcus Aurelius · Meditations

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The passage locates goodness within the person and compares it to a fountain. Continued digging is the condition for its continuing flow. One reading is that looking inward requires persistent effort: the source may be internal, but drawing on it is presented as active work.
Context reviewed