What I have garnered here is that we have three distinct bodies. A physical, astral and causal body. When we are working with Kriya or similar techniques we are speaking of more subtle energies than those associated with the physical spine. For instance when we feel a wave of exhilaration up our spine...this is more than a physical sensation. Paramahansa Yogananda has stated that all the deeds and actions/ inactions we have done in all our innumerable life times are stored in the astral spine. Practicing one Kriya correctly gives an accelerated evolution towards enlightenment. Because it burns out the seeds of past karma just lying there and awaiting the right circumstances to manifest in our earthly sojourns. One Kriya done correctly erases a year of natural evolution in the physical realm.
However, Kriya Yoga is more direct. It helps the practitioner to control the life force by mentally drawing that life force up and down the spine, with awareness and will. According to Yogananda, one Kriya, which takes about a half a minute, is equivalent to one year of natural spiritual growth.
