Thirukkural 511

நன்மையும் தீமையும் நாடி நலம்புரிந்த தன்மையான் ஆளப் படும்.

Nanmaiyum theemaiyum naadi nalam purintha thanmaiyaan aalap padum.

One who discerns what is good and what is harmful, and acts to bring about benefit, commands authority through that very nature.