Kural - 421

True wisdom wards off woes, A circling fortress high;
Its inner strength man's eager foes Unshaken will defy

Explanation
Wisdom is a weapon to ward off destruction; it is an inner fortress which enemies cannot destroy.

Tamil Transliteration
421 Arivatrang Kaakkung Karuvi Seruvaarkkum
Ullazhikka Laakaa Aran.