Yoga is a single word covering a multitude of practices. All are based on the principle of yoking the mind to one idea or one object; but since the ideas selected differ with the different schools of teaching, the results are often strikingly at variance. For concentrated thought gives increased power to our present qualities, intensifying the beliefs with which we started. Hence the competing schools of occultism with their clashing doctrines.
-- Notebooks Category 4: Elementary Meditation > Chapter 1: Preparatory > # 113