It is just like this with the whole mechanism of the universe. It is audible all the time; it is visible both externally and inwardly. As it is said in the Psalms, speaking of the heavens, "There is neither speech nor language: but their voices are heard among them. Their sound is gone out into all lands: and their words into the ends of the world." But we are so concerned with our own activities, with the things we ourselves are interested in, that our consciousness can only retain these and pays no attention to all the other things, loud as they are.