Kural - 452

The waters' virtues change with soil through which they flow;
As man's companionship so will his wisdom show

Explanation
As water changes (its nature), from the nature of the soil (in which it flows), so will the character of men resemble that of their associates.

Tamil Transliteration
Nilaththiyalpaal Neerdhirin Thatraakum Maandharkku
Inaththiyalpa Thaakum Arivu.