Sun Tzu was a Chinese military general of the 6th Century BC. He is is thought to have authored a book titled, “The Art of War,” which became a traditional source of reference on military strategy in the Chinese world. In more recent years, the book also gained a wide audience in the west.
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.