Yoga has been practiced in India since prehistoric times according to evidence from the Indus Valley. While the ritualistic parts of the Vedas do not mention yoga, the Upanishads is where yoga is first found. Yoga combines theory and practical application, with clear knowledge of theory being essential to properly practice yoga. The Kathopanishad specifically mentions Adhyatma Yoga, or meditation on the inner self, stating that control of the senses is yoga and leads to freedom from the mind's vagaries. Yoga is meant for the welfare of all mankind.