In every man there are latent faculties by means of which he may acquire for himself knowledge of the higher worlds. The mystic, master, theosophist, or gnostic speaks of a soul-world and a spirit-world, which are, for him, just as real as the world which we see with our physical eyes, or touch with our physical hands. And those who wish to develop the spiritual senses, which unfold psychic knowledge, should understand that safe advice can be given only by those who have already developed such power within themselves. As long as the human race has existed, there have been lodges and schools in which those who possessed these higher faculties have given instruction to those who were in search of them. Such are called occult schools, and the instruction which is imparted therein is called esoteric science, or occult teaching. This designation sometimes leads to misunderstanding. He who hears it may be very easily misled into the belief that those who work in these schools desire to represent a special, privileged class, which arbitrarily withholds its knowledge from its fellow-creatures. Indeed, he may even think that perhaps there is nothing really important behind such knowledge. For he is tempted to think that, if it were a true knowledge, there would be no need of making a secret of it: one might then communicate it publicly to the advantage of all men. Those who have been initiated into occult knowledge are not in the least surprised that the uninitiated should so think. Only he who has to a certain degree experienced this initiation into the higher knowledge of being can understand the secret of that initiation. But it may be asked: How, then, shall the uninitiated, considering the circumstances, develop any interest at all in this so-called mystic knowledge? How and why ought they to search for something of the nature of which they can form no idea? Such a question is based upon an entirely erroneous conception of the real nature of occult knowledge. There is, in truth, no fundamental difference between occult knowledge and all the rest of man's knowledge and capacity. This mystic knowledge is no more a secret for the average man than writing is a secret to him who has never learned to read. And just as everyone who chooses the correct method may learn to write, so too can everyone who searches after the right way become a disciple, and even a teacher. In only one respect are the conditions here different from those that apply to external thought-activities. The possibility of acquiring the art of writing may be withheld from someone through poverty, or through the state of civilization into which he has been born; but for the attainment of knowledge in the higher worlds there is no obstacle for him who sincerely searches for it.