For hundreds of years, the inner spiritual core of Islam has been the focus of Sufi practitioners and thinkers. Those initiated into its mysteries have sometimes expressed them in ecstatic poetry, in a symbolic language of love, or in reasoned prose. These essays by such contemporary writers on Sufism as Seyyed Hossein Nasr, William Chittick, Titus Burckhardt, Martin Lings, René Guénon, and Frithjof Schuon, allow the reader to understand the language, the wisdom, and the beautiful history of classical Sufism. Covering a wide range of topics related to the mystical aspect of Islam, Sufism, this book includes essays on spiritual thought and knowledge, many of which have been translated into English for the first time. Several of the contributions are from a new generation of interpreters and wisdom seekers of Sufism.