The Sūfī conception of the passing-away (fanā) of individual self in Universal Being is certainly, I think, of Indian origin. Its first great exponent was the Persian mystic, Bāyazīd of Bistām, who may have received it from his teacher, Abū ʿAlī of Sind (Scinde). Here are some of his sayings:
“Creatures are subject to changing ‘states,’ but the gnostic has no ‘state,’ because his vestiges are effaced and his essence annihilated by the essence of another, and his traces are lost in another’s traces.”
“Thirty years the high God was my mirror, now I am my own mirror,” i.e. according to the explanation given by his biographer, “that which I was I am no more, for ‘I’ and ‘God’ is a denial of the unity of God. Since I am no more, the high God is His own mirror.”
“I went from God to God, until they cried from me in me, ‘O Thou I!’”
This, it will be observed, is not Buddhism, but the pantheism of the Vedānta. We cannot identify fanā with Nirvāṇa unconditionally. Both terms imply the passing-away of individuality, but while Nirvāṇa is purely negative, fanā is accompanied by baqā, everlasting life in God. The rapture of the Sūfī who has lost himself in ecstatic contemplation of the divine beauty is entirely opposed to the passionless intellectual serenity of the Arahat. I emphasise this contrast because, in my opinion, the influence of Buddhism on Mohammedan thought has been exaggerated. Much is attributed to Buddhism that is Indian rather than specifically Buddhistic: the fanā theory of the Sūfīs is a case in point. Ordinary Moslems held the followers of Buddha in abhorrence, regarding them as idolaters, and were not likely to seek personal intercourse with them. On the other hand, for nearly a thousand years before the Mohammedan conquest, Buddhism had been powerful in Bactria and Eastern Persia generally: it must, therefore, have affected the development of Sūfism in these regions.
While fanā in its pantheistic form is radically different from Nirvāṇa, the terms coincide so closely in other ways that we cannot regard them as being altogether unconnected. Fanā has an ethical aspect: it involves the extinction of all passions and desires. The passing-away of evil qualities and of the evil actions which they produce is said to be brought about by the continuance of the corresponding good qualities and actions. Compare this with the definition of Nirvāṇa given by Professor Rhys Davids:
“The extinction of that sinful, grasping condition of mind and heart, which would otherwise, according to the great mystery of Karma, be the cause of renewed individual existence. That extinction is to be brought about by, and runs parallel with, the growth of the opposite condition of mind and heart; and it is complete when that opposite condition is reached.”
Apart from the doctrine of Karma, which is alien to Sūfism, these definitions of fanā (viewed as a moral state) and Nirvāṇa agree almost word for word. It would be out of place to pursue the comparison further, but I think we may conclude that the Sūfī theory of fanā was influenced to some extent by Buddhism as well as by Perso-Indian pantheism.
The receptivity of Islam to foreign ideas has been recognised by every unbiassed inquirer, and the history of Sūfism is only a single instance of the general rule. But this fact should not lead us to seek in such ideas an explanation of the whole question which I am now discussing, or to identify Sūfism itself with the extraneous ingredients which it absorbed and assimilated in the course of its development. Even if Islam had been miraculously shut off from contact with foreign religions and philosophies, some form of mysticism would have arisen within it, for the seeds were already there. Of course, we cannot isolate the internal forces working in this direction, since they were subject to the law of spiritual gravitation. The powerful currents of thought discharged through the Mohammedan world by the great non-Islamic systems above mentioned gave a stimulus to various tendencies within Islam which affected Sūfism either positively or negatively. As we have seen, its oldest type is an ascetic revolt against luxury and worldliness; later on, the prevailing rationalism and scepticism provoked counter-movements towards intuitive knowledge and emotional faith, and also an orthodox reaction which in its turn drove many earnest Moslems into the ranks of the mystics.
How, it may be asked, could a religion founded on the simple and austere monotheism of Mohammed tolerate these new doctrines, much less make terms with them? It would seem impossible to reconcile the transcendent personality of Allah with an immanent Reality which is the very life and soul of the universe. Yet Islam has accepted Sūfism. The Sūfīs, instead of being excommunicated, are securely established in the Mohammedan church, and the Legend of the Moslem Saints records the wildest excesses of Oriental pantheism.