IChing
The Book of Changes or the IChing in its essence expounds that everything is naturally and constantly transforming through the interaction of yin and yang.
The IChing: "...holds that when events proceed to their extremes they give birth to their opposites..." *1
Thus it reveals the Tao of change and teaches us how to behave in society, about ourselves and how to be prepared and perceive when situations change and the influencing forces at play that cause this transformation.
Above all the IChing is one of the most amazing psychological, metaphysical, sociological and philosophical books ever printed and it's also an Oracle!
The first evidence of the IChing were turtle shells used in divination dating back to over 2,500 years BC. Then the oracle only chose between yes and no or yin and yang. Through many centuries the Tao of I has evolved to 64 pictographs or hexagrams that relate to the interaction and changes in the forces of nature. A poem found in Hexagram 61 is shown below.
"To the Chinese, the IChing is like a Holy Bible written by the four most honoured sages in [Chinese] history - Fu Xi, King Wen, the Duke of Zhou and Confucius. Chinese understand that Ching is the Tao, the Truth, the holiest of the ancient books..."*1
Hexagram 61: Zhong Fu (Innermost Sincerity)
"Confucius says:
Under Heaven, only the person possessing the most complete sincerity and trustworthiness is able to fully develop his true nature. If one is able to fully develop his true nature, he is able to fully develop the nature of other people. If one is able to fully develop the nature of other people, he is able to fully develop the nature of all creatures. In so doing, he is able to be involved in Heaven and Earth's transformational and nourishing functions and become one with heaven and earth."*1
The IChing and the way of Tao is:
"The Embodiment of the Principles of Heaven & Earth: Initiating and Responding with the qualities of vitality and persistence, extending and responding. In correspondence with this:
Keep vital without ceasing and enrich virtue to sustain all beings.
*1 = source: "The Complete IChing", by Alfred Huang. Published by Inner Traditions International.