Intangible Waves:

The simplest waves to think about are the ones we can observe and feel. Water waves are the best illustration. When you sit on a beach where enlarges are rolling in, you can feel their rhythm and force. The Prehistoric humans no doubt spend hours staring at the waves on oceans and lakes, surprising where they came from, why they were at times big and at times small, why they were at times smooth and other times choppy, why they at times came from the west and other times came from the north, and why they at times shifted with the wind and other times moved against the wind.

Visualize a child, 100,000 years ago, dipping a pebble into a pond or watching a fish jump and observing that the ripples originating from the disturbance were just similar to ocean swells, but smaller. This should have been a surprising, though it was nothing compared to the discoveries scientists would afterward make with the help of mathematics, instruments, and an attraction with the intangible.