Earth, Wind, Fire and Water are the quintessential natural forces of nature.
We can see the earth, fire and water but not the Wind.

Who has seen the wind, neither your nor I
Do we have to see it to believe it?
Who Has Seen the Wind?
BY CHRISTINA ROSSETTI
Who has seen the wind?
Neither I nor you:
But when the leaves hang trembling,
The wind is passing through.
Who has seen the wind?
Neither you nor I:
But when the trees bow down their heads,
The wind is passing by.
In response to The Daily Post’s weekly photo challenge: “Forces of Nature.”