“Does everything make a sound?” asked the young man, as he noticed how falling rocks made a sound, rattling off each other.
“Everything vibrates, even that rake over there,” replied the gardener.
“How can a rake vibrate?”
“Go and rake the pebbles in the garden, then you shall hear it singing.”
So the young man set about raking the pebbles in the garden. As he did so, he noticed how each time he lifted the rake and placed it down to move the pebbles, he heard a high pitched tone and he noticed how metal against pebble made the noise.
“I can hear the rake singing! Yet it only sings when it’s in contact with the stones and pebbles. Why is this?”
“Ah, this is because it takes two to communicate, otherwise the rake would be singing to itself.”