cause, is a procedure that no logic would justify. Let us, therefore, in the light of a truer theory of causation, enumerate the principal political, social, and intellectual conditions of Islamic life about the end of the 8{th} and the first half of the 9{th} century when, properly speaking, the Ṣūfī ideal of life came into existence, to be soon followed by a philosophical justification of that ideal.-- (1). When we study the history of the time, we find it to be a time of more or less political unrest. The latter half of the 8{th} century presents, besides the political revolution which resulted in the overthrow of the Umayyads (749 A.D.), persecutions of Zendīks, and revolts of Persian heretics (Sindbāh 755–6; Ustādhīs 766–8; the veiled prophet of Ḵẖurāsān 777–80) who, working on the credulity of the people, cloaked, like Lamennais in our own times, political projects under the guise of religious ideas. Later on in the beginning of the 9{th} century we find the sons of Hārūn (Ma’mūn and Amīn) engaged in a terrible conflict for political supremacy; and still later, we see the Golden Age of Islamic literature seriously disturbed by the persistent revolt of the Mazdakite Bābak (816–838). The early years of Ma’mun's reign present another social phenomenon of great political significance--the S̱ẖu‘ūbiyya controversy (815), which progresses with the rise and establishment of independent Persian families, the Tāhirīd (820), the Ṣaffārīd (868), and the Sāmānīd Dynasty (874). It is, therefore, the combined force of these and other conditions of a similar nature that contributed to drive away spirits of devotional character from the scene of continual unrest to the blissful peace of an ever-deepening contemplative life. The semitic character of the life and thought of these early Muhammadan ascetics is gradually followed by a large hearted pantheism of a more or less Aryan stamp, the development of which, in fact, runs parallel to the slowly progressing political independence of Persia. (2). _The Sceptical tendencies of Islamic Rationalism_ which found an early expression in the poems of Bas̱ẖs̱ẖār ibn Burd--the blind Persian Sceptic who deified fire, and scoffed at all non-Persian modes of thought. The germs of Scepticism latent in Rationalism ultimately necessitated an appeal to a super-intellectual source of knowledge which asserted itself in the Risāla of Al-Qus̱ẖairī (986). In our own times the negative results of Kant's Critique of Pure Reason drove Jacobi and Schleiermacher to base faith on the feeling of the reality of the ideal; and to the 19{th} century sceptic Wordsworth uncovered that mysterious state of mind "in which we grow all spirit and see into the life of things".