Gurudev Paramahansa Yogananda

 The “doors” spoken of here correspond to the spinal Chakras - astral centers of light, consciousness, and energy sometimes called “lotuses” because of their petal-like outer filaments. Ordinarily these petals hang downward, but when the consciousness of the deeply meditating yogi enters the spine and begins its marvellous ascent through each chakra to the higher centers in the brain, the petaldoors turn upward or “open” themselves. Each chakra is characterized by a distinctive light, sound, and state of consciousness. The intuitive divine realizations bestowed on the yogi as he passes through these spinal doors drive away from the body temple the “dark bird” of spiritual ignorance.

Cosmic Chants, Page No. 9
by Beloved Gurudev Paramahansa Yogananda