London Lectures of 1907

" ...]will evolve in every human being the power of using the astral body as freely as you use the physical body now, so can you quicken the coming of that day for yourselves by understanding the powers of thought and turning them to the object you desire to obtain. There are many ways in which this may be done, and many rules you may learn for your guidance. Those rules may be summed up under two heads: clear and strenuous thinking, discipline for the bodies that you are trying to evolve; and also, I should add, for the body below them in evolution. Those are the two great laws for the safe evolution of these so-called psychic powers, what I call the powers of the consciousness on the astral and mental planes. ...]."