In proceeding to the contemplation of the mysteries of knowledge, we shall adhere to the celebrated and venerable rule of tradition, commencing from the origin of the universe, setting forth those points of 
physical contemplation which are necessary to be premised, and removing whatever can be an obstacle on the way; so that the ear may be prepared for the reception of the tradition of the Gnosis, the ground 
being cleared of weeds and fitted for the planting of the vineyard; for there is a conflict before the conflict, and mysteries before the mysteries.—S. Clement of Alexandria.