Celestial (Flex-5) The term celestial has many different meanings: relating to the sky, space or the heavens. All of these things can be used to describe what is brought out by the performance of this piece. This theme goes through a number of transformations throughout the piece and gives the performers the opportunity to work on many elements and styles of performing, from light dynamics and articulations, into something that is meant to be played with more energy and heaviness.