The prophets and great mystics have come to the world from time to time as the physician comes to help the patient whose health is in disorder. And each time the great ones have come they have brought to the world another life, a new life brought to the whole organism of the universe to help it to run smoothly. The Sufis who in all times have existed as mystics, whose lives have been devoted to meditation and spiritual practices - what have they learned from these meditations? They have learned the essence of all, the oneness or unity, and in unity - in thinking it, realizing it and living it - one fulfils the purpose of life.