Who makes it, has no need of it.
Who buys it, has no use for it.
Who uses it can neither see nor feel it.

To protect his country a king decided to build a wall made out of stone along the border. The wall had to be 3 meters thick and 5 meters high. The border of the country has a length of 500 kilometers. Assuming that one cubic meter of stone weights about 3000 kg, how much heavier becomes the earth by building this wall?

My love, when I gaze on thy beautiful face,
Careering along, yet always in place
The thought has often come into my mind
If I ever shall see thy glorious behind.

What am I talking about?