This work is one in the Voice of Inayat series. While under the guidance of Pir-o-Murshid Inayat Khan, the bearer of the Sufi message to the Western world, it was the author's great privilege to hear from his voice things of the essential truth taught by all the great teachers of the world. Recognizing the value of his lectures, and considering of how great importance they would be during this time of the world's spiritual reawakening, the author tried to put on paper a record of them and presents them to the readers of the world.