The old Romans used to tell this strange story. There was a nymph, or kind of fairy, called Echo, who was the daughter of the Earth and the Air. She was at first a favourite with the great god, Jupiter; but his queen, Juno, was jealous of her, and made her so that she could not speak unless someone spoke to her. Echo fell in love with a beautiful youth called Narcissus, but Narcissus loved only himself, and spent all his time gazing at the image of his face in a clear pool of water, and would not look at poor Echo. So poor Echo pined away and was changed into a stone, but as a stone, she could still repeat any words that were spoken to her. As for Narcissus, he was changed into a flower (the “Nargis”) as a punishment for his pride.
This was the way the Romans tried to explain echoes. In some places in valleys in the mountain, or in towns where the streets are shut in by tall buildings, or in large halls and rooms, the sounds we make are repeated and come back to us. When we shout against a tall rock, the sound of our voice comes back to us; and in a quiet street in a town, we can often hear our footsteps repeated as we walk along. Some echoes are very clear and good; they repeat not only a single shout, but whole sentences. If we say, “Who are you?” the echo answers quite clearly in our own voice, “Who are you?”
What is an echo? Well, the old explanation was that is a nymph or fairy that was in the mountain, and that mocked people when they called by repeating their words. But of course, that is only a fairy tale, and we know better. Sometimes boys at play throw a ball against a high wall. The ball strikes the wall and bounces back into their hands. Something like this happens when an echo answers us. We throw the sound of our voice at the tall rock, and the sound, so to speak, bounces back from the rock into our ears. Sound does not travel very fast through the air; so it takes a little time to reach the rock and come back again to us. That is why we hear our words repeated a little time after we have said them. The Romans were right anyway in this: that an echo is the daughter of the earth and the air.