The main problem is that most commentators are accustomed to thinking of

The main problem is that most commentators are accustomed to thinking of spiritual schools as ‘systems’, which are more or less alike, and which depend upon dogma and ritual: and especially upon repetition and the application of continual and standardised pressures upon their followers.The Sufi way, except in degenerate forms which are not to be classified as Sufic, is entirely different from this.