A Sumerian Riddle (an excerpt from the book)

Here is a 4000-year-old riddle. What could be its answer?

A house with a foundation like heaven,
A house which like a copper kettle has been covered with linen,
A house which like a goose stands on a firm base,
He whose eyes are not open has entered it,
He whose eyes are wide open comes out of it.

The answer is school. This enigmatic riddle and its answer were discovered on a clay tablet excavated from the ancient Sumerian city of Ur. Although the full comprehension of the first three lines of the riddle may elude a modern reader, the meaning of the latter two lines is readily apparent.