In mystical terms the two different directions of the breath have been called by different names, and have been considered to be like the sun and the moon, representing the positive and negative aspects of the power and influence of breath. How few really know how many times in the day and night the breath changes its direction, and how it works through different parts of mind and body producing different effects and results. How often man's ignorance of the science of breath makes him act or think or speak against its influence - which is like swimming against the tide. We often notice in life that at one time success is achieved by the least little effort, and at another the greatest effort produces nothing but failure.