In Dzogchen, a fundamental point of practice is to distinguish rigpa from sems ("citta", (grasping) mind). According to the 14th Dalai Lama, ""sems" is the mind which is temporarily obscured and distorted by thoughts based upon the dualistic perceptions of subject and object." "Rigpa" is pure awareness free from such distortions. "Cittata", the nature of mind, is the inseparable unity of awareness and emptiness, or clarity and emptiness, which is the basis for all the ordinary perceptions, thoughts and emotions of the ordinary mind.