The Mystic

An engineer, a physicist, a mathematician, and a mystic were asked to
name the greatest invention of all times.

The engineer chose fire, which gave humanity power over matter.

The physicist chose the wheel, which gave humanity the power over space.

The mathematician chose the alphabet, which gave humanity power over
symbols.

The mystic chose the thermos bottle.

"Why a thermos bottle?" the others asked.

"Because the thermos keeps hot liquids hot in winter and cold liquids
cold in summer."

"Yes -- so what?"

"Think about it." said the mystic reverently. That little bottle --
how does it know?"