Sri Aurobindo
Letters of Sri Aurobindo
3. The Mother and the Practice of the Integral Yoga
When the Peace is established, this higher or Divine Force from above can descend and work in us. It descends usually first into the head and liberates the inner mind centres, then into the heart centre and liberates fully the psychic and emotional 
being, then into the navel and other vital centres and liberates the inner vital, then into the Muladhara and below and liberates the inner physical being. It works at the same time for perfection as well as liberation; it takes up the whole nature part by part and deals with it, rejecting what has to be rejected, sublimating what has to be sublimated, creating what has to be created. It integrates, harmonises, establishes a new rhythm in the nature. It can bring down too a higher and yet higher force and range of the higher Nature until, if that be the aim of the sadhana, it becomes possible to bring down the supramental force and existence. All this is prepared, assisted, farthered by the work of the psychic being in the heart centre; the more it is open, in front, active, the quicker, safer, easier the working of the Force can be. The more love and bhakti and surrender grow in the heart, the more rapid and perfect becomes the evolution of the sadhana. For the descent and transformation imply at the same time an increasing contact and union with the Divine.
That is the fundamental rationale of the Sadhana. It will be evident that the two most important things here are the opening of the heart centre and the opening of the mind centres to all that is behind and above them. For the heart opens to the psychic being and the mind centres open to the higher consciousness and the nexus between the psychic being and the higher consciousness is the principal means of the Siddhi. The first opening is effected by a concentration in the heart, a call to the Divine to manifest within us and through the psychic to take up and lead the whole nature. Aspiration, prayer, bhakti, love, surrender are the main supports of this part of the Sadhana – accompanied by a rejection of all that stands in the way of what we aspire for. The second opening is effected by a concentration of the consciousness in the head (afterwards, above it) and an aspiration and call and a sustained will for the descent of the divine Peace, Power, Light, Knowledge, Ananda into the being – the Peace first or the Peace and Force together. Some indeed receive Light first or Ananda first or some sudden pouring down of Knowledge. With some there is first an opening which reveals to them a vast infinite Silence, Force, Light or Bliss above them 
and afterwards either they ascend to that or these things begin to descend into the lower nature. With others there is either the descent, first into the head, then down to the heart level, then to the navel and below and through the whole body, or else an inexplicable opening – without any sense of descent – of peace, light, wideness or power or else a horizontal opening into the cosmic consciousness or, in a suddenly widened mind, an outburst of knowledge. Whatever comes has to be welcomed – for there is no absolute rule for all,– but if the peace has not come first, care must be taken not to swell oneself in exultation or lose the balance. The capital movement however is when the Divine Force or Shakti, the Power of the Mother comes down and takes hold, for then the organisation of the consciousness begins and the larger foundation of the Yoga.
11 September 1934