The old truth which was known to the ancients, but which had been almost entirely forgotten during our modern age of materialism, that man is not a finished being, incapable of any further organic development, but that his body and his mind are continually subject to transformation and change, and that no transformation can take place where no substance exists, because force cannot exist without substance, has become almost universally known.

Franz Hartmann, With The Adepts: An Adventure Among the Rosicrucians