Sri Aurobindo
Letters of Sri Aurobindo
Volume III - Part 1
It [feeling that the Mother and Sri Aurobindo are looking at one] 
simply means you have a subjective sense of our Presence. But must a subjective sense of things be necessarily a vain imagination? If so, no Yoga is possible. One has to take it as an axiom that subjective things can be as real as objective things. No doubt there may be and are such things as mental formations – but, to begin with, mental formations are or can be very powerful things, producing concrete results; secondly whether what one sees or hears is a mental formation or a real subjective object can only be determined when one has sufficient experience in these inward things.