A Classical Feng Shui practitioner relies on the use of a Lo-Pan (compass) to determine one of 24 directions a structure is sitting and facing.  Assessments are not subjective but are based on the year an individual is born, the surrounding environment, and the movement of the solar system. The principles in Traditional Feng Shui includes an in-depth understanding and application of the theories of Yin and Yang, balancing the Five Elements (fire, earth, metal, water and wood), East-West Compass Directions, the Solar System and the environment known as Form School Feng Shui.  Harmony is achieved based upon a set of theories and complex calculations derived from the Yi Jing, the Chinese Book of Change. A Classical Feng Shui practitioner uses calculations according to these principles to make determinations.  Remedies are prescribed where necessary to balance the energy flow so that the environment has a positive effect on those residing within.