In volume 1 | book 2, Islamic Literature in the Arabic Language | Section 1, The Classical Period from ca. 750 until ca. 1000
A. Merx, Idee und Grundlinien einer allgemeinen Geschichte der Mystik, Inaugural address, Heidelberg 1893.
L. Massignon, Taṣawwuf, EI IV, 737/42.
Alongside the traditional ritualistic piety of the oldest version of Islam and under the pressure of the political and social crises of the first two centuries there developed at an early stage a spiritual movement that, based on a deeper stud…