When a musician who normally writes music for a piano and vocals takes away the vocal or melody line you end up with a piece of music in which you have to piece all the elements together to get the melody line. In ‘Foreward: They Moved the Underground’ Robert Schumann uses the two piano lines to piece together different elements of the melody as the other piano lines work by incorporating small elements of the melody but staying off the direct line to show the melody where to follow. The incorporation of the two pieced together gives an approximate melody line that we as listeners can patch together.

An even more simple way of describing what is occurring in this is through the use of a bird in cage spinning toy also known as a Victorian Thaumatrope. This is a toy which uses two different images to make one when spun. In the same way the two music lines join together to make the melody. Yet it does not express what would happen if it was played back with the melody and one line removed as it would show in this case.

An example of this which also incorporates pure absence and structural absence is through colour. When aiming for a finished product to be the colour green we can eliminate the green and show the mixing of the two outside colours of yellow and blue which make green. When having the colour green in front of you as well as the outside colour of yellow you may technically know that there is blue in it but there is no representation of this as the green may have come premixed.