This chapter deals with an intellectual movement, Guénonian Traditionalism, which I will refer to for short merely as ‘Traditionalism’ (with a capital T, in order to distinguish it from the many other forms of traditionalism that exist). 1 Traditionalism was one of the earliest European producers of Islamic knowledge, with publications appearing in Paris and Cairo before the First World War. It is not, however, a form of Islam, but rather a Western philosophical and religious movement that often expresses itself in Islamic terms. 2 It appears at ﬁ rst sight to be a movement calling for a return to true religion in general, and to Suﬁ Islam in particular, in reaction to the evils of the modern world. It was developed by a French philosopher – René Guénon – who was active in Paris before and after the First World War, and who moved to Cairo in 1930. He died there in 1951, a respected Muslim, cited as a model of Suﬁ piety by no less an authority than Abd al-Halim Mahmud, supreme shaykh of the Azhar ( Mahmud 1974 ). As we will see, however, there is more to Traditionalism than at ﬁ rst meets the eye.