To secure ourselves against defeat lies in our own hands, but the opportunity of defeating the enemy is provided by the enemy himself.

孫子曰：昔之善戰者，先為不可勝，以侍敵之可勝。不可勝在己，可
勝在敵。故善戰者，能為不可勝，不能使敵之必可勝。故曰：勝可知