Mme. Blavatsky:

... TRANSMISSION, NOT REVELATION ...

More than one great scholar has stated that there never was a religious founder, whether Aryan, Semitic or Turanian, who had invented a new religion, or revealed a new truth. These founders were all transmitters, not original teachers. They were the authors of new forms and interpretations, while the truths upon which the latter were based were as old as mankind. Selecting one or more of those grand verities -- actualities visible only to the eye of the real Sage and Seer -- out of the many orally revealed to man in the beginning, preserved and perpetuated in the adyta of the temples through initiation, during the MYSTERIES and by personal transmission -- they revealed these truths to the masses. Thus every nation received in its turn some of the said truths, under the veil of its own local and special symbolism; which, as time went on, developed into a more or less philosophical cultus, a Pantheon in mythical disguise. 

--Secret Doctrine