Thanks to Aparna for this link. Srinivas talks about how Rahman composed this song. This is one of my favorites too.

Lyrics of this song

kanavaa illai kaatra
kanavaa nee kaatra

kaiyil midhakkum kanavaa nee
kai kaal muLaiththa kaatraa nee
kaiyil yaendhiyum ganakkavillaye
nurayaal seidha silayaa nee
ippadi unnai yaendhi koNdu indhira logam poi vidavaa
idayil konjam vali eduthaalum chandira tharayil paai idava

(kaiyil)

nilavil poruL edai izhakkum
neerilum poruL edai izhakkum
kaadhalil kooda edai izhakkum indru kaNdenadi
adhai kaNdu koNdenedi

(nilavil)

kaadhal thaaimai iraNdu mattum
baaram enbadhai aRiyaadhu
un paLingu mugaththai paarthu koNdaal
pasiyum valiyum theriyaadhu

(kaadhal)

unnai mattum sumandhu nadandhaal
uyaram dhooram theriyaadhu
unnai mattum sumandhu nadandhaal
uyaram dhooram theriyaadhu
un mael vandhu oar poo vizhundhaal
ennaal thaanga mudiyaadhu

(kaiyil)