Have you ever sat by a river and watched the mesmerizingly graceful movement of the river grasses, which surrender themselves completely to the flow of the river?

At their base they are firmly attached to a rock on the riverbed. If they were not securely attached in this way, they would be carried away by the current and would perish.

The upper part of these grasses has absolutely no resistance and is thus free to flow in an infinite variety of movements caused by …