"The qualifications for admission to the Great White Brotherhood, which have to be acquired in the course of the work in the earlier part of the Path, are of a very definite character, and are always essentially the same, although they have been described in many different terms during the last twenty-five centuries. In the early days of The Theosophical Society, when all its wonderful teaching was new to us, this question of qualifications was naturally one of those about which some of us were most eager to learn; and before Madame Blavatsky wrote down for us that most marvellous manual The Voice of the Silence"
January 1, 1970
https://en.wikiquote.org/wiki/The_Masters_and_the_Path