Sri Aurobindo
Letters of Sri Aurobindo
Volume III - Part 3
X’s experiences are those which usually attend the withdrawal from the outer consciousness into an inner plane of experience. The feeling of coldness of the body in the first is one of the signs – like the immobility and stiffness of Y’s experience – that the consciousness is withdrawing from the outer or physical sheath and retiring inside. The crystallisation was the form in which he felt the organisation of an inner consciousness which could receive at once firmly and freely from above. The crystals at once indicate organised formation and a firm transparence in which the greater vision and experience descending from the higher planes could be clearly reflected.
As for the other experience, his rejection of the waking consciousness evidently had the result of throwing him into an 
inner awareness in which he began to have contact with the supraphysical planes. What was meant by the sea of red colour and stars depends on the character of the red colour. If it was crimson, what he saw was the sea of the physical consciousness and physical life as it is represented to the inner symbolic vision; if it was purple red, then it was the sea of the vital consciousness and the vital life-force. Perhaps, if he had not stopped his sense of the Mother’s presence, it would have been better,– he should rather, if he can, take it with him into the inner planes, then he would have had no occasion to fear.
In any case, if he wants to go into the inner consciousness and move in the inner planes – which will inevitably happen if he shuts off the waking consciousness in his meditation – he must cast away fear. Probably he expected to get the silence or the touch of the divine consciousness by following out the suggestion of the Gita. But the silence or the touch of the divine consciousness can be equally and for some more easily got in the waking meditation through the Mother’s presence and the descent from above. The inward movement, however, is probably unavoidable and he should try to understand and, not shrinking or afraid, to go to it with the same confidence and faith in the Mother as he has in the waking meditation. His dreams are of course experiences on the inner (vital) plane.
P.S. The dream about the Mahadeva image may mean that someone (not of this world, of course) wanted to mislead him and make him confuse some narrower traditional form of the past with the greater living Truth that he is seeking.