The breath has a great influence and entire control over two principles which work by the power of the breath: Qabs, or contraction, and Bast, or expansion. The former absorbs, attracts, and gathers energy from outside, the latter tendency expels energy from within. In this way body and mind are sustained, nourished, enriched, and made light, easy, clear and pure by the power of breath. Inhaling is contraction and exhaling is expansion. It is upon these two principles and their regular working that the health and happiness of man depend.