‘Mysticism means to isolate the eternal from the originated.’ This is not my definition of the word ‘mysticism’ but that of the founder of the ‘orthodox’ school of Muslim mysticism, Al-Junayd of Baghdad who flourished in the ninth century a.d. In actual fact it is not a definition of mysticism at all but of the Arabic word tawḥīd which means primarily ‘the affirmation of unity’; and that surely is an essential ingredient of any form of mysticism: it is the affirmation through personal experience of unity either absolutely or in some qualified sense.