To-day Zen as a living faith can be found in its pure form only among the Japanese Buddhists. You cannot find it in the so-called Gospel of Buddha anymore than you can find Unitarianism in the Pentateuch, nor can you find it in China and India any more than you can find life in fossils of bygone ages. It is beyond all doubt that it can be traced back to Shakya Muni himself, nay, even to pre-Buddhistic times, because Brahmanic teachers practised Dhyana, or Meditation, from earliest times.
