"Sufi mystics and Zen masters would, I suspect, understand the feeling"

  Sufism is the common name for Muslim mysticism, and its practitioners are Sufis or Dervishes. They believe that it is possible to become close to God in life, rather than only death, and seek to obtain a state of perfection within themselves by sticking closely to the path of God.

Zen masters teach Zen Buddhism, a form of Buddhism which focuses on wisdom in helping to achieve enlightenment. It too aims to achieve a state of perfection in the mind.