Maharishi Mahesh Yogi:

“The practice (of Transcendental Meditation) involves thinking of a word, a word devoid of meaning.

Meaning is a static thing. The sound changes in its pitch—it can be loud sound, or low sound. The meaning is the same at every pitch. If the mind is on the meaning, there is no chance of refining the meaning. If the mind is not on the meaning, there is a chance of refining the sound, there is a chance of experiencing the sound in its finer values till the finest could be transcended and the awareness could reach that inner wakefulness devoid of any perception. This will be Transcendental Consciousness….

This unbounded awareness where the perception is no longer within boundaries—it is unbounded. This is a silent state of the mind, and it is so fulfilling that the physiology having tasted this kind of quietness of activity it cherishes that. And because it is cherishing to the whole physiology, to the whole experience, the physiology tends to maintain that state naturally even when there are activities. So by nature that state is experienced, and by nature, through practice, it becomes stabilized in the field of activity….

The whole thing is very simple. It is an absolutely natural process.”