Daniel Barenboim: Sound has several very interesting aspects, I think, worth observing. One is duration—that there is a connection between sound and time. But before that there is a connection between sound and silence. When one speaks about sound, very one speaks of the color of sound— a bright sound or a dark sound. Which is of course nonsense because what may be dark for one is light for the other, and vice versa. It's very subjective. I could say "It's a beautiful sound." What is a beautiful sound? So it's very subjective and not really a definable characterization. Whereas the duration of sound and it's relation to silence is a very objective thing. I sing a note or I whistle a note and when I have no more air, the note goes. Where does it go? Into the silence again. And when we observe that really more clearly we see that sound has a relationship with silence not unlike the law of gravity. In order to lift a certain object from the ground we have to use energy. But then to sustain it at that level, we have to keep on adding energy or otherwise the object falls to the ground. It's exactly the same thing with the sound. We need a certain amount of energy to produce the sound. But then to sustain it we have to give more energy or otherwise it goes and it dies in silence. And therefore sound is absolutely, inextricably connected to time, the length of time. And this, I think, what gives it or even more so when it becomes music. It's really tragic element of the fact that it can die, of the fact that it is a lifetime. Every note is a lifetime for itself.