When he utilizes combined energy, his fighting men become as it were like unto rolling logs or stones. For it is the nature of a log or stone to remain motionless on level ground, and to move when on a slope; if four-cornered, to come to a standstill, but if round-shaped to go rolling down.
Sun TzuNow a soldier's spirit is keenest in the morning; by noonday it has begun to flag; and in the evening, his mind is only on returning to camp.
Sun TzuIf you know yourself but not the enemy, for every victory gained you will also suffer a defeat.
Sun Tzu