If you know neither the enemy nor yourself, you will succumb in every battle
Hence the saying: One may know how to conquer without being able to do it.
Know the enemy and know yourself; in a hundred battles you will never peril.
Attack him where he is unprepared, appear where you are not expected.
Place your army in deadly peril, and it will survive; plunge it into desperate straits, and it will come off in safety.
Victory is reserved for those who are willing to pay its price.