Kural - 396

In sandy soil, when deep you delve, you reach the springs below;
The more you learn, the freer streams of wisdom flow

Explanation
Water will flow from a well in the sand in proportion to the depth to which it is dug, and knowledge will flow from a man in proportion to his learning.

Tamil Transliteration
Thottanaith Thoorum Manarkeni Maandharkkuk
Katranaith Thoorum Arivu.