Vidura pointedly warned Yudhishthira in words intelligible only to the prince:"He alone will escape from danger who forestalls the intentions of an astute enemy. There are weapons sharper than those made of steel. And the wise man who would escape destruction must know the means to guard against them. A large disastrous fire that devastates a forest cannot hurt a rat which shelters itself in a hole or a porcupine which burrows in the earth. The wise man knows his bearings by looking at the stars."
From the Mahabharata of Vyasa
