[55:1] Macdonald's Muslim Theology, p. 161. 2. Ṣūfīism--an appeal to a higher source of knowledge which was first systematised by Ḏẖu’l-Nūn, and became more and more deepened and antischolastic in contrast to the dry intellectualism of the As̱ẖ‘arite. We shall consider this interesting movement in the following chapter. 3. The revival of authority--Ismā‘īlianism--a movement characteristically Persian which, instead of repudiating freethought, endeavours to come to an understanding with it. Though this movement seems to have no connection with the theological controversies of the time, yet its connection with freethought is fundamental. The similarity between the methods practised by the Ismā‘īlian missionaries and those of the partisans of the association called Iḵẖwān al-Safā--Brethren of Purity--suggests some sort of secret relation between the two institutions. Whatever may be the motive of those who started this movement, its significance as an intellectual phenomenon should not be lost sight of. The multiplicity of philosophical and religious views--a necessary consequence of speculative activity--is apt to invoke forces which operate against this, religiously speaking, dangerous multiplicity. In the 18th century history of European thought we see Fichte, starting with a sceptical inquiry concerning the nature of matter, and finding its last word in Pantheism. Schleiermacher appeals to Faith as opposed to Reason, Jacobi points to a source of knowledge higher than reason, while Comte abandons all metaphysical inquiry, and limits all knowledge to sensuous perception. De Maistre and Schlegel, on the other hand, find a resting place in the authority of an absolutely infallible Pope. The advocates of the doctrine of Imāmat think in the same strain as De Maistre; but it is curious that the Ismā‘īlians, while making this doctrine the basis of their Church, permitted free play to all sorts of thinking.