Heaven, Earth, Man.
天-地 - 人
This appears p.73 of "The Art of the Warrior: Leadership and Strategy from the Chinese Military Classics" Translated and Edited by Ralph D. Sawyer. This passage is indeed worthy of study.
"The Sage takes his signs from the movements of Heaven and Earth; who knows his principles? He accords with the Tao of yin and yang, and follows their seasonal activity. He follows the cycles of fullness and emptiness of Heaven and Earth, taking them as his constant. All things have life and death in accord with the form of Heaven and Earth. Thus it is said that if one fights before seeing the situation, even if he is numerous, he will certainly be defeated.
One who excels at warfare will await events in the situation without making any movement. Whe he sees he can be victorious he will arise; if he sees he cannot be victorious he will desist. Thus it is said he doesn't have any fear, he doesn't vacillate. Of the many harms that can beset an army, vacillation is the greatest. Of disasters that befall an army, none surpasses doubt."
- The Six Secret Teachings
"The Sage takes his signs from the movements of Heaven and Earth; who knows his principles? He accords with the Tao of yin and yang, and follows their seasonal activity. He follows the cycles of fullness and emptiness of Heaven and Earth, taking them as his constant. All things have life and death in accord with the form of Heaven and Earth. Thus it is said that if one fights before seeing the situation, even if he is numerous, he will certainly be defeated.
One who excels at warfare will await events in the situation without making any movement. Whe he sees he can be victorious he will arise; if he sees he cannot be victorious he will desist. Thus it is said he doesn't have any fear, he doesn't vacillate. Of the many harms that can beset an army, vacillation is the greatest. Of disasters that befall an army, none surpasses doubt."
- The Six Secret Teachings