Thirukkural-On Wealth-On Education-Kural 396

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The wells in the sand abound with springs of water as one digs deep,
So with appropriate education, knowledge gets wider and deeper.

The deeper one digs on the sand-beds, generally on the dry bed of a river, the greater will be the flow of water. Apparently, Valluvar must have been familiar with the process of digging sand – wells on the dry beds of the rivers, like Vaigai and Palar, to secure drinking water. This analogy, the poet uses with good effect to draw a parallel to the cultivation of the mind, through a process of extensive and intensive education.

Another possible way of interpreting the Kural is that, unless you put your hand to it, the sand-well will not produce water; in like manner, acquisition of knowledge and its development can only be the result of a the application of one"s mind. Physical idleness will not produce water; mental idleness similarly will surely not produce knowledge.

Kambaramayanam elaborates this idea of learning in the following line, as indicated by K V Jaganathan.
“Noolvaraith thodarndhu bayathodum pazagi,
Nunangiya nuvalarum unarvae" (Kamba, Nagarap, 8)