The Kundalini is like a rope with many threads. She rises by unfolding her coils piercing every chakra. The width of the Kundalini or the number of threads start diminishing as She ascends if the higher chakras are not open or if the piercing points in the chakras are constricted. If the lower chakras are open the Kundalini rises as a whole, but if the higher chakras are not open then the constriction does allow few threads to pass. So it is very necessary to have at least the lower chakras cleansed. In the western mind the higher chakras are better but as their Mooladhara chakra is in jeopardy, the force is very weak and their own sensitivity very poor.
When the kundalini rises without any hurdles, it reaches the Agnya and spreads on the lower brain plate like a cloud, so a heaviness or sleepy feeling crawls. I say that first the mother puts you to sleep. The second feeling is when the vital force of Kundalini melts down over the Ida and Pingala. As if the cloud of the vital force starts pouring bliss. Gradually the head feels as if the lead is being taken off. One feels relaxed. Now again these two channels carry it down up to nabhi and now a new force from Kundalini joins it. … Then the triple force rises which opens the agnya. At this time eyes get closed. The pupils start dilating.
Now the head gets clearer but some feel a mild pressure or throbbing at Sahastrara. The agnya crossing creates the thoughtless awareness. You feel the silence of Sahastrara. At Sahastrara the Kundalini accumulates. A kind of release starts as the Brahmarandra (fontanel bone) opens. It works slowly with some, but with most of them it is with a gush. At that moment, the sadhaka (disciple) feels the cool breeze of the vibrations. This is “realization”. There are many who have got jagruti (awakening) and have got the curing power but they cannot remain in thoughtless awareness. They touch it for a minute or so. But the process of Kundalini oozing out works out with time and ultimately they reach a stage of doubtless awareness.
With some like X it was a quick permanent ascent, he felt as if two bath of ice fell on his hands and started melting. The cooling crawled into his Being. If the Visshuddhi is doubtful or stretched and constricted, then, one does not feel the vibrations despite realization, meaning the piercing of the Brahmarandra.. The collective consciousness is felt even before the Kundalini pierces the Brahmarandra fully. You start feeling the burning on the fingers and also the discriminating styles of collective consciousness are manifested.
H.H.Shri Mataji Nirmala Devi, Letter to a follower, London, 1977