Sri Aurobindo
Letters of Sri Aurobindo
Volume III - Part 1
You have written of the Force coming down [during a period of 
emptiness] – even sometimes of its filling all parts – so what is this “never”? I did not at all mean that there is a mechanical process by which every time there is emptiness afterwards there comes an entire filling up. It depends on the stage of the sadhana. The emptiness may come often or stay long before there is any descent – what fills may be silence and peace or Force or Knowledge and they may fill only the mind or mind and heart or mind and heart and vital or all. But there is nothing fixed and mechanically regular about these two processes.