Know the enemy and know yourself; in a hundred battles you will never be in peril. When you are ignorant of the enemy, but know yourself, your chances of winning or losing are equal. If ignorant both of your enemy and yourself, you are certain in every battle to be in peril.

It is said that if you know your enemies and know yourself, you will not be imperiled in a hundred battles; if you do not know your enemies but do know yourself, you will win one and lose one; if you do not know your enemies nor yourself, you will be imperiled in every single battle.

If you know neither the enemy nor yourself, you will succumb in every battle.

Nothing is as dangerous as an ignorant friend; a wise enemy is to be preferred.

An unsuspected enemy is doubly dangerous.

It is what you do not know that is your greatest risk.

Hence the saying: If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle.

It is not for us that we exhort you to learn, but for yourself, because ignorance is an inability, a real disaster, because social positions and protection are no longer there as before, there is a ground for malice and even hatred.

It is not honourable to attack an enemy without putting yourself at risk.

The one thing that is more dangerous than true ignorance is the illusion of understanding.

Beware of false knowledge; it is more dangerous than ignorance.

He that is not aware of his ignorance, will be only misled by his knowledge.

Ignorance is fatal.

It is worse still to be ignorant of your ignorance.