The instructions for yoga in the Indian Vedas and Upanishads, especially in the Bhagavad Gītā, the sublime dialogue between the master of heaven and the son of earth, offer some of the deepest wisdom regarding human nature and spiritual awakening. Franz Hartmann, the greatest German mystic of the 19th century, argues that what has been taught in the Bhagavad Gītā has been taught especially emphatically and convincingly by the great mystic of the 13th century, Meister Eckhart. Hartmann shows that the path to the realization of "Christ in us" and the yoga teachings in the Bhagavad Gītā is almost identical.