Knowledge is found not only through the reading of books, but via personal instruction from an authorized source. One can obtain a logical knowledge from codex, but the techniques of opening the centers of higher perception are not taught in books: they are acquired from communication with an authentic mystery school. An example of this would be reading The Rosicrucian Cosmo-Conception by Max Heindel: the secrets of the ages and the history of the planet and Man are relieved, but the techniques of perception are not taught in the book.
The student of the mystery school, known as an initiate, receives knowledge from masters of the organization and is taught the techniques of unfolding the latent powers within him or her and learns to use these powers for the good of others. The knowledge must be shared amongst others who are ready to receive such knowledge: those who are ready must come to the school on their own initiative. The secrets must not be taught to just anyone – be careful to whom you expose the mysteries: do not “cast your pearls before swine”. Secret knowledge in the wrong hands can have bad consequences and can cause the knowledge to be perverted for selfish ends and can then cause great harm.
Secret knowledge is spiritual knowledge. It is for the humble ones who have prepared themselves for receiving it over a long span of time.