When we experience something in the physical body, it is a sensation that carries a nervous impulse to the brain, which interprets whether it is cold or hot, dry or wet, painful or pleasurable, etc. Similarly, vital reactions and emotions are experienced through the release of various hormones into the bloodstream which travel to the brain and create the vital experience. When the mind is active, various parts of the brain become activated through the release of neuro-transmitters which activate various nerve pathways and thereby create the sense of memory, creative imagination, will, or thought that indicates an active mental process. We cannot “see” any of these reactions or experiences but we trust them through training and habit to be real and meaningful for our individual life processes and decision-making skills. Humanity has also created a collective understanding of shared experience and thus, we determine the reality of the physical, vital and mental experiences based on this shared experience.
When it comes to spiritual experience, therefore, the issue is not that we perceive it in some totally different way, but that the experience itself is something that goes outside our normal, habitual bounds for what the body, life and mind accept as normal and usual. Some of these experiences are very much felt in a physical way, such as the descent of a force from above, while others are more subtle such as the feeling of a deep peace overwhelming the being, or a spontaneous uprush of adoration or devotion. The experience of the Kundalini energy has been reported to be something that is physically palpable. One of the primary characteristics of spiritual experiences, in fact, is the absolute authenticity with which they present themselves to the awareness. Some may be very intense, some may be overwhelming, while others are quite subtle in their action, but all of them are incontrovertibly real to those who experience them. Another factor to consider is that spiritual experiences have been reported independently, throughout the world, throughout humanity’s history, and collectively there is a body of evidence that validates the reality of these experiences, taking them outside the realm of pure subjectivity without an external basis.
Sri Aurobindo notes: “This inward movement takes place in many different ways and there is sometimes a complex experience combining all the signs of the complete plunge. There is a sense of going in or deep down, a feeling of the movement towards inner depths; there is often a stillness, a pleasant numbness, a stiffness of the limbs. This is the sign of the consciousness retiring from the body inwards under the pressure of a force from above, — that pressure stabilising the body into an immobile support of the inner life, in a kind of strong and still spontaneous asana. There is a feeling of waves surging up, mounting to the head, which brings an outer unconsciousness and an inner waking. It is the ascending of the lower consciousness in the Adhara to meet the greater consciousness above. It is a movement analogous to that on which so much stress is laid in the Tantric process, the awakening of the Kundalini, the Energy coiled up and latent in the body and its mounting through the spinal cord and the centres (cakras) and the Brahmarandhra to meet the Divine above. In our yoga it is not a specialised process, but a spontaneous uprush of the whole lower consciousness sometimes in currents or waves, sometimes in a less concrete motion, and on the other side a descent of the Divine Consciousness and its Force into the body. This descent is felt as a pouring in of calm and peace, of force and power, of light, of joy and ecstasy, of wideness and freedom and knowledge, of a Divine Being or a Presence — sometimes one of these, sometimes several of them or all together.”
Sri Aurobindo, Integral Yoga: Sri Aurobindo’s Teaching and Method of Practice, Chapter 7, Experiences and Realisations, The Inward Movement, pp. 174-179