The first time the actual use of the term feng shui appears in any ancient text was from a passage found in the Book of Burial, written by Guo Po in the 4th century.
"Qi rides the feng (wind) and scatters, but is retained when Encountering shui (water)"
The principal of feng shui states that a geographic site that attracts water is optimal, followed by the site that catches the wind. It is these two elements that effect and shape our environment, which is alive with the hidden force of chi.
Chi is often a difficult concept to define. It is often described as, vital breath, or life energy. It is found in the environment and is carried by the flow of air. Strong winds can disperse chi and water can retain it. Barriers, such as, mountains, buildings, walls or furniture can block the movement of chi.
Steven Post writes in his book, Modern Book of Feng Shui, that in “Chinese calligraphy, chi is depicted as steam rising over rice, which provides nourishment.” It is this essence that nourishes and energizes nature, creativity and existence. It is the intrinsic substance or the vital breath behind all things in the universe.