Silence is not merely negative -- a pause between words, a temporary cessation of speech -- but properly understood, it is highly positive: an attitude of attentive alertness, of vigilance, and above all, of listening.
~ Kallistos Ware
What do we call visible light? We call it color. But the electromagnetic spectrum runs to zero in one direction and infinity in the other, so really, children, mathematically, all of light is invisible.