Texts might prove misleading if studied alone; they must be personally expounded by a competent teacher. Moreover, if but two books, for instance, out of thirty, were taken alone they would give a one-sided and inaccurate picture. But the book by Sri Krishna Prem, Yoga of the Bhagavad Gita, can be quite helpful. The aim of The Hidden Teaching Beyond Yoga is to prepare a basis, to create an atmosphere, but it does not go farther than that. There is a lower mysticism and a higher mysticism and the two are separated in time by the philosophic discipline. Nothing of the higher mysticism has been revealed in The Hidden Teaching Beyond Yoga. That is given in The Wisdom of the Overself together with several practices or exercises which develop the supramystic insight hinted at as being the final source of knowledge. Neither mysticism as ordinarily known--that is, the lower mysticism and yoga--nor philosophy of a purely intellectual-rational kind can ever lead to this goal. Nevertheless they are essential stages on the way thereto. One must not make the mistake either of discarding meditation (as recommended by Ashtavakra) and resorting only to ratiocination, or of despising ratiocination (as ordinary mystics and yogis do) and trusting solely to meditation. Both are needed. But both are only preliminary disciplines. Only the supramystic exercises can lead to the final revelation and these were given to the West for the first time in The Wisdom of the Overself. They were formerly kept esoteric in every sense of the word, but times have changed.
-- Notebooks Category 20: What Is Philosophy? > Chapter 4: Its Realization Beyond Ecstasy > # 34