It is the Alpha or Omega.

Just as the mouth opens for the A,

so the process of creation is opened by this word.

It is the maintained by the U and comes to a close with the M.

Similarly AUM symbolizes the three relative states of waking, dreaming and deep sleep.

Yet beyond these,OM also has fourth a soundless aspect.

In this aspect, it symbolizes the a absolute silence from which the word is born.