The purpose of meditation, I was taught, is to feel the stirrings of the thought-bubbles forming in our subconscious, thereby allowing us to dissipate them gently before they breach the surface of our consciousness and thus disturb the equanimity of our mind. Learning to discipline "the thought-stuff of the mind" in this manner affords us a certain discipline over our thought, speech and actions.
In his commentary on the "Bhagavad-Gita," the Maharishi describes "the main principle" of TM in the following terms:
"The technique may be defined as turning the attention inwards towards the subtler levels of thoughts until the mind transcends the experience of the subtlest state of the thought and arrives at the source of the thought. This expands the conscious mind and at the same time brings it in contact with the creative intelligence that gives rise to every thought.""It should be noted," the Maharishi points out, "that transcendental meditation is neither a matter of contemplation nor of concentration. The process of contemplation and concentration both hold the mind on the conscious thinking level, whereas transcendental meditation systematicaly takes the mind to the source of thought, the pure field of creative intelligence."
"A thought-impulse starts from the silent creative centre within, as a bubble starts from the bottom of the sea. As it rises, it becomes larger; arriving at the conscious level of the mind, it becomes large enough to be appreciated as a thought, and from there it develops into speech and action."
"Turning the attention inwards takes the mind from the experience of a thought at the conscious level . . . to the finer states of the thought, until the mind arrives at the source of thought. . . . This inward march of the mind results in the expansion of the conscious mind."