Brahmacharya-A state of the individual where the life-force is always found directed upwards. MMY Gita appendix.
Bal Brahmacharya-One who has practiced celibacy from childhood. Why is that significant? The prana (life-force) is that subtle essence that connects the soul to the body. The consciousness is tied to the prana and as such the prana, when withdrawn from the body during TM allows the mind to experience subtler states of consciousness. If the prana is caught up in sexual fantasies it becomes 'tied down' to body consciousness, this 'addiction' expresses itself as the samskaras or vrittis in the subconscious mind disallowing the mind to transcend, these are the 'stresses' MMY is talking about that must be 'released' to free the mind from bondage to material desire. As such, by practicing the Yama number 4 or Celibacy, the aspiring Yogi can accelerate the release of consciousness from attachments that 'tie' him/her to body consciousness. These attachments hold the prana (tied up in the lower chakras; lust, anger and greed) and as a result hold the awareness, trapping it in body consciousness. This is one of the *means* to Yoga recommended by Maharishi Patanjali! If you're serious about Yoga, "With the continuous practice of ALL these limbs, or *means*, simultaneously, the state of Yoga grows simultaneously in all the eight spheres of life," MMY Gita/Yoga appendix, direct quote!
