The Purpose of Life by Paramahansa Yogananda
The purpose of life is to ascend the six spinal centers, reinforcing the human consciousness progressively with greater and greater lights, until it is able to unite with the all-pervading, thousand-rayed brilliance in the highest center in the brain.
This ascent of the consciousness through the spine may be achieved slowly through right actions and right thoughts. The yogi, however, chooses the quicker and more scientific method of meditation.
The internal consciousness of ordinary people operates only from the lumbar, sacral, and coccygeal centers that direct all material sensory perceptions and enjoyments.
The divine lovers and celestial poets work from the heart center.
The calm unshaken yogi operates from the cervical center.
He who can feel his presence in the entire vibratory creation has awakened the medullary and Christ centers.
The illumined yogi functions in the cerebral center of Cosmic Consciousness; he may be spoken of as an ascended yogi.
(p.372, God Talks With Arjuna: The Bhagavad Gita by Paramahansa Yogananda) — Read more at: http://www.yogananda.com.au/pyr/pyr_kundalini1.html