The elders who want wood must be solid; What does it mean that people who want to go far must dig their own fountains?
The elders who want wood must be solid; Those who want to flow far away will dig their springs.
From: "Ten Thoughts on Emperor Taizong".
It means: if you want a tree to grow tall, you must stabilize its foundation; If you want the river to flow forever, you must dredge the source; To stabilize the country, we must accumulate people's hearts.