Sri Aurobindo
Letters of Sri Aurobindo
Volume III - Part 4
This is a fundamental experience of the Yoga. It is the free ascent of the consciousness to join the Divine. When, liberated from its ordinary identification with the body, it rises upward to have experiences of the higher planes, to link itself with the psychic or the true being or to join the Divine Consciousness, then there is this experience of ascension and of speeding or expanding through space. The joy you feel is a sign of this last movement,– rising to join the Divine; the passivity and expectancy of a 
descent are signs of the openness to the Divine that is its result; there is also the sense of this openness, an emptiness of the ordinary contents of the consciousness, a wideness not limited by the narrow prison of the physical personality. There is too, usually or very often, a massive immobility of the body which corresponds to the silence that comes on the mind when it is released from itself – the Silence that is the foundation of spiritual experience. What you have felt (the former experiences were probably preparatory touches) is indeed the beginning of this foundation – a consciousness free, wide, empty at will, able to rise into the supraphysical planes, open to the descent of whatever the Mother will pour into it.