Sri Aurobindo
Letters of Sri Aurobindo
Volume III - Part 4
An entire silence and inactivity of the mind cannot come at first – what is possible is a quietude of the mind, that is to say, a cessation of its absorption in its restless miscellaneous activity of ill-connected or unconnected thoughts and a concentration on the object of the sadhana. The imagination which the Mother recommended to you was a means of such concentration. A 
mental idea of the omnipresence such as comes to you is a good help for that also, especially if it brings the strong faith and reliance. The feeling of the vibration of the Mother’s Force around the head is more than a mental idea or even a mental realisation, it is an experience. This vibration is indeed the action of the Mother’s Force which is first felt above the head or around it, then afterwards within the head. The pressure means that it is working to open the mind and its centres so that it may enter. The mind centres are in the head, one at the top and above it, another between the eyes, a third in the throat. That is why you feel the vibration around the head and sometimes up to the neck, but not below. It is so usually, for it is only after enveloping and entering the mind that it goes below to the emotional and vital parts (heart, navel etc.) – though sometimes it is more enveloping before it enters the body. To see the light in the heart one has to go deep, but one can see light elsewhere without going in deep there. Light is often seen between the eyebrows first or in front at that level, for there is the centre of inner vision and a slight opening of it is sufficient for that – so also light is often seen round the head or above it, outside.