The consciousness of the mind, life, body in each person is ordinarily shut up in itself; it is narrow, not wide, sees itself as the centre of everything, judges all things according to its own impressions—it does not know anything as it really is. But when by Yoga one begins to open to the true consciousness, then this barrier begins to break down. One feels the mind grow wider, even in the end the physical consciousness grows wider and wider, until you feel all things in yourself, yourself one with all things. You then become one with the Mother’s universal Consciousness. That is why you feel the mind becoming wide.
But also there is much above the human mind and it is this which you feel like a world above your head. All these are the ordinary experiences of our Yoga. It is only a beginning. But in order that it may go on developing, you must become more and more quiet, more and more able to hold whatever comes without getting too eager and excited. Peace and calmness are the first thing, and with it wideness—in the peace you can bear whatever love or Ananda comes, whatever strength comes or whatever knowledge.
Ref: Letters on Yoga – I