Why Compose Each Part Individually?

It is clearly asserted by Ligeti that he wanted to control his ``soundscape'' in a very precise way.

He wanted it to have the right ``light, color, texture'' and, maybe more importantly the right ``evolution''.

In that aim, every part had to be accurately composed in every detail. The overall sound-space's range being from the bottom to the top notes of all instruments of a complete orchestra, one may think of it, at first, as a quadrilateral area where the height (y-axis) is the pitch and the width (x-axis) is the time.

Figure: Symbolic representation of the usage of the total sound-space

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This over-simplistic view, to truly represent the musical thinking of Ligeti, has to be completed by the missing sound-parameters: tone-color (instrumental resources, playing dynamic); event-density; internal animation^3.1. Those parameters are evolving and can be continuously changing within the shape as well. So there is no real way to represent it graphically.

This aspect of continual changes and evolution is what makes the Ligeti soundscapes first and unique in the history.