Songfacts®:

• This song finds Enya musing on the cycle of the universe and how change affects everything. Her producer Nicky Ryan recalled: "It began when, after writing the melody line, Enya started humming a small part of the melody."
  
  "It's rather appropriate as the title refers to the sound of the early universe which is at around 47 octaves below the lowest note on the piano keyboard. Scientists have compressed this extremely low frequency vibration that the Planck space telescope picked up so that it would be audible to us. It has a humming sound."
• Lyricist Roma Ryan: "The title refers to the sound of our early universe. Obviously, the sound is totally inaudible to the human ear, but scientists have now been able to compress their findings from the Planck Space Telescope, so that they can give us an audible rendering of the waves at the beginning of our universe, the result of which could be described as a constant humming sound."
  
  "The lyric moves on from this beginning and muses on how, from the smallness of the sub-atomic domain to the gigantic regions of the heavens, there is a certain irony that one constant in the flow of existence is change. One thing can become another. Atoms can become molecules. The two elements of Hydrogen and Oxygen can become water."
  
  "At the end of its cycle of life as a sun, the sun itself can change to become a supernova. These supernovae seed our planets and earthforms. Trees decay and fall, and from their demise a family of fungi arise to help with regeneration in the cycle of life. Clouds that are born from risen water can then dissolve into rain, which falls to become river or ocean, which once again, in some part, becomes the risen water forming the clouds. Man is only one part of the whole cycle. What a wonderful, complex system surrounds him."