The science of the mind:

Predominantly concerned with the control of the mind through following the path of ethical perfection and regular practice on concentration and meditation.

Raja Yoga is a practical guide for gaining control over the mind. The second sutra states, "Yogas chitta vritti nirodhah," or, "The restraint of the modifications of the mind-stuff is Yoga." Every thought, feeling, perception, or memory you may have causes a modification or a ripple in the mind. It distorts and colours the mental mirror. If you can restrain the mind from forming into modifications, there will be no distortion, and you will experience your true Self.