When speaking of the various current theories as to the origin of Ṣúfiism, I said that in my opinion they all contained a measure of truth. No single cause will account for a phenomenon so widely spread and so diverse in its manifestations. Ṣúfiism has always been thoroughly eclectic, absorbing and transmuting whatever 'broken lights' fell across its path, and consequently it gained adherents amongst men of the most opposite views--theists and pantheists, Mu‘tazilites and Scholastics, philosophers and divines. We have seen what it owed to Greece, but the Perso-Indian elements are not to be ignored. Although the theory "that it must be regarded as the reaction of the Aryan mind against a Semitic religion imposed on it by force" is inadmissible--Dhu ’l-Nún, for example, was a Copt or Nubian--the fact remains that there was at the time a powerful anti-Semitic reaction, which expressed itself, more or less consciously, in Ṣúfís of Persian race. Again, the literary influence of India upon Muḥammadan thought before 1000 A.D. was greatly inferior to that of Greece, as any one can see by turning over the pages of the _Fihrist_; but Indian religious ideas must have penetrated into Khurásán and Eastern Persia at a much earlier period. These considerations show that the question as to the origin of Ṣúfiism cannot be answered in a definite and exclusive way. None of the rival theories is completely true, nor is any of them without a partial justification. The following words of Dr. Goldziher should be borne in mind by all who are interested in this subject:-- [Sidenote: Goldziher on the character of Ṣúfiism.] "Ṣúfiism cannot be looked upon as a regularly organised sect within Islam. Its dogmas cannot be compiled into a regular system. It manifests itself in different shapes in different countries. We find divergent tendencies, according to the spirit of the teaching of distinguished theosophists who were founders of different schools, the followers of which may be compared to Christian monastic orders. The influence of different environments naturally affected the development of Ṣúfiism. Here we find mysticism, there asceticism the prevailing thought."[731] The four principal foreign sources of Ṣúfiism are undoubtedly Christianity, Neo-platonism, Gnosticism, and Indian asceticism and religious philosophy. I shall not attempt in this place to estimate their comparative importance, but it should be clearly understood that the speculative and theosophical side of Ṣúfiism, which, as we have seen, was first elaborated in ‘Iráq, Syria, and Egypt, bears unmistakable signs of Hellenistic influence. [Sidenote: Báyazíd of Bisṭám.]