Because anarchism is in its essence an anti-dogmatic and unstructured cluster of related attitudes, which does not depend for its existence on any enduring organization, it can flourish when circumstances are favourable and then, like a desert plant, lie dormant for seasons and even for years, waiting for the rains that will make it burgeon. Unlike an ordinary political faith, in which the church-party becomes the vehicle of the dogma, it does not need a movement to carry it forward…

Postscript (July 1973) - Anarchism : A History of Libertarian Ideas and Movements (1962)