The Supremely Profound Principal deeply permeates all species of things but its physical form cannot be seen. It takes nourishment from emptiness and nothingness and derives its life from Nature. It penetrates the past and present and originates the various species. It operates yin and yang and starts the material force in motion. As yin and yang unite, all things are complete on Heaven and on Earth. The sky and sun rotate and the weak and strong interact. They return to their original position and thus the beginning and end are determined. Life and death succeed each other and thus the nature and the destiny are made clear. Looking up, we see the form of the heavens. Looking down, we see the condition of the earth. We examine our nature and understand our destiny. We trace our beginning and see our end. ... Therefore the Profound Principle is the perfection of utility.
To see and understand is wisdom. To look and love is humanity. To determine and decide is courage. To control things universally and to use them for all is impartiality. To be able to match all things is penetration. To have or not to have the proper circumstance is destiny. The way by which all things emerge from vacuity is the Way. To follow the principles of the world without altering them and to attain one's end is virtue. To attend to life, to be in society, and to love universally is humanity. To follow order and to evaluate what is proper is righteousness. To get hold of the Way, virtue, humanity, and righteousness and put them into application is called the business of life. To make clear the achievement of nature and throw light on all things is called yang. To be hidden, without form, deep and unfathomable, is called yin. Yang knows yang but does not know yin. Yin knows yin but does not know yang. The Profound Principle alone knows both yin and yang, both going and stopping, and both darkness and light.
~ Tai Hsuan Ching (Classic of the Supremely Profound Principle) (9)7: 5a-9b