Breathing is one internal function that the conscious mind can control with comparative ease. The effect of controlled breathing is almost like communication with all conscious parts of one's being saying to them, "Simmer down and listen; there is something beyond the turmoil". It is communication in action that often works when words merely go in one ear and out the other, not even changing the cognitive mind. In essence, the effect is to turn all the elements of our will toward stillness and waiting.
To be a contemplative is to be a watch in the night for the approach of Mystery. And it is a readiness to be transformed in an engagement with that Mystery.
~ Fr. Iain Matthew in DARK NIGHT OF THE SOUL, newly translated by Mirabai Starr