In a cave, all outer sounds are smothered by rock and earth, but this makes the sounds of one's own heartbeat and breath audible. In the same way, contemplative stillness turns us away from everyday clamor but allows us to hear the subtle in our own lives. When listening not with the ear but with the spirit, one can perceive the subtle sound. By entering into that sound, we enter into supreme purity. That is why so many religious traditions pray, sing, or chant as a prelude to silence. They understand that the repetition and absorption of sound leads to sacredness itself. The deepest sound is silence. This may seem paradoxical only if we regard silence as an absence of life and its opposites. It is both sound and soundlessness, and it is in this confluence that the power of meditation emerges.
In the Sahara one day, I climbed over a dune to descend into a deep bowl of sand. Sitting at the bottom I encountered for the first time absolute silence, stillness that is indivisible. For there are two silences: a silence can be no more than the absence of noise, it can be inert; or, at the other end of the scale, there is a nothingness that is infinitely alive, and every cell of the body can be penetrated and vivified by this second silence's activity.