Yoga, an ancient but perfect science, deals with the evolution of humanity.  This evolution includes all aspects of one's being, from bodily health to self-realization.  Yoga means union - the union of body with consciousness and consciousness with the soul.  Yoga cultivates the ways of maintaining a balanced attitude in day-to-day life and endows skill in the performance of one's actions.  ~ Shri B.K.S. Iyengar.