நன்றி ஒருவர்க்கு செய்தக்கால்---when you do some good deed

நன்றி ஒருவர்க்கு செய்தக்கால் அந்நன்றி
என்று தருங்கொல் என வேண்டா நின்று தளரா
வளர் தெங்கு தாளுண்ட நீரைத்
தலையாலே தான் தருதலால்.

nandri oruvarku cheidakkal annandri
endru tarun kol ena vaenda -nindru talara
valartengu taaLunda neerai
talaiyale thaan tarudalaal.
 
When you do something good to someone
don't do it with the expectation that they will reciprocate ;
Think of the coconut tree. Someone pours water at its root;
It grows tall for years without giving anything in return ;
After years it starts giving back in the form of water and flesh inside.

That is the literal meaning.

But thinking of the analogy provokes more thoughts.

The tree takes water from someone and takes some years to grow. He may be a mere gardener doing it for an employer in which case he may not be around to enjoy the fruit. If he is an old man, he too may not be around when the coconuts are harvested. The fruits are enjoyed by some who may or may not be connected with the planter. But the planter tends to the plant in spite of knowing that he may not be the one to enjoy the fruits. Similarly when you do some good deed do it wholeheartedly bearing in mind you may are may not be able to enjoy the benefits of the deed.

That is from the planter's or giver's angle;
And from the taker's angle--- when you receive something good from someone, be it in kind or any other form of help, you may not be able to reciprocate in the same way to the same person. But you can definitely do that to people who need it like the coconut tree taking water from someone and giving the benefits to much more people.