Through yoga or meditation, one arrives at mind-control. Then he takes his sharpened, concentrated mind and applies it to the understanding of the world. Thus he discovers that the world of matter is ultimately space and that all material forms are merely ideas in his mind. He discovers, also, that his inmost self is one with this space, because it is formless. Then does he perceive the unity of all life, and only then has he found Truth--the whole truth. All this must be discovered by experience, not by intellectual theory, and here his power to control thoughts becomes important . . . first to make the mind absolutely still, then to use this exceedingly sharpened mind to survey and penetrate the truth of things. That is why neither mysticism nor yoga can lead directly to Truth. They are only preparations for the higher path that does lead to Truth.
-- Notebooks Category 20: What Is Philosophy? > Chapter 4: Its Realization Beyond Ecstasy > # 130