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.
It is not outer reality that silence reveals, but our own innerness. Silence is essentially a surrender to the holiness of the divine mystery – whether we use these words or not. An atheist, calming his or her spirit in the peace of silence, is irradiated by the same mystery, anonymous but transforming. We are to listen. To what? To silence.