yogash chitta vritti nirodhah
yogash- to join, to integrate
chitta- the screen of mind that consciousness observes
vritti- fluctuations, changes, modifications
nirodhah- mastery, control, regulation, channeling
My Translation:
Yoga is the art of channelling the fluctuations of mind in order to achieve an undisturbed, peaceful state of mind.
Chitta is the screen on which our world plays. We do not see the world as directly as we think. What we see is a combination of sensory input and memory. Our senses do not give us complete information, but our minds fill in the missing gaps from memory. All too often though, the screen is disturbed by memories that are not necessarily relevant to the reality we are attempting to perceive. By a threefold process of letting go, observing without attachment, and finally inspecting these memories when they present themselves, one can gradually weaken their control over the mind. When this is done with sincere effort, but without straining, peace of mind can be achieved.