„From now on it is impossible to think of sounds as defined object s which are mutually interchangeable. They strike me rather as force fields given direction in time. These forces – I purposely use this word and not the word form – are infinitely mobile and fluctuating; they are alive like cells, with a birth, life and death, and above all tend towards a continual transformation of their own energy. There exists no sound which is static, immobile, any more than the rock strata of mountains are immobile.
By definition, we will say that sound is transitory. […] What would bring us to a better definition of sound would be the knowledge of the energy which inhabits it and of the network of correlations which govern all its parameters . One can imagine an ecology of sound, like a new science placed at the disposal of musicians.“

Gérard Grisey: „Tempus ex Machina: A composer’s reflections on musical time“ in:  Contemporary Music Review  2:1 (1987), p. 239-275, here: p. 268-269.