Series 1, Chapter 23 pg 242, Para 2: This peace of Nirvana is reached when all the mental consciousness is perfectly controlled and liberated from desire and remains still in the Self, when, motionless like the light of a lamp in a windless place, it ceases from its restless action, shut in from its outward motion, and by the silence and stillness of the mind the Self is seen within, not disfigured as in the mind, but in the Self, seen, not as it is mistranslated falsely or partially by the mind and represented to us through the ego, but self-perceived by the Self, svaprakasa. Then the soul is satisfied and knows its own true and exceeding bliss, not that untranquil happiness which is the portion of the mind and the senses, but an inner and serene felicity in which it is safe from the mind's perturbations and can no longer fall away from the spiritual truth of its being. Not even the fieriest assault of mental grief can disturb it; for mental grief comes to us from outside, is a reaction to external touches, and this is the inner, the self-existent happiness of those who no longer accept the slavery of the unstable mental reactions to external touches. It is the putting away of the contact with pain, the divorce of the mind's marriage with grief, duhkha-samyoga-viyogam. The firm winning of this inalienable spiritual bliss is Yoga, it is the divine union; it is the greatest of all gains and the treasure beside which all others lose their value. Therefore is this Yoga to be resolutely practised without yielding to any discouragement by difficulty or failure until the release, until the bliss of Nirvana is secured as an eternal possession.