The sketches presented in this book contain practically no full biographical information of any kind about the lives of its subjects. They are devoted to research about their mission, message and what the Sufis call the Work. I wrote about those whom I consider to be really great mystics although not all of them are recognized as such. I didn’t begin to limit myself to only an analysis of the activity of specific Teachers, but included in the book several essays on the later stages of the Sufi Way and methods of transmitting knowledge. In my view, they enable the reader to understand more fully and deeply the situation in which any real mystic finds himself. In this book, I propose answers to many questions that I know for sure torment many seekers. I hope that it will be useful to them as for all those in general who are interested in the Way – in the widest most sense of that word. After all, the experience of the Work of every mystic is the most valuable knowledge, available to us in an ordinary state of perception.