These exercises are for those who are not mere beginners in yoga. Such are necessarily few. The different yogas are successive and do not oppose each other. The elementary systems prepare the student to practise the more advanced ones. Anybody who tries to jump all at once to the philosophic yoga without some preliminary ripening may succeed if he has the innate capacity to do so but is more likely to fail altogether through his very unfamiliarity with the subject. Hence these ultramystic exercises yield their full fruit only if the student has come prepared either with previous meditational experience or with mentalist, metaphysical understanding--or better still with both. Anyone who starts them, because of their apparent simplicity, without such preparation must not blame the exercises if he fails to obtain results. They are primarily intended for the use of advanced students of metaphysics on the one hand or of advanced practitioners of meditation on the other. This is because the first class will understand correctly the nature of the Mind-in-itself which they should strive to attain thereby, whilst the second class will have had sufficient self-training not to set up artificial barriers to the influx when it begins.
-- Notebooks Category 23: Advanced Contemplation > Chapter 6: Advanced Meditation > # 8
-- Perspectives > Chapter 23: Advanced Contemplation > # 37