This figure, taken from the dome of the NAS building’s Great Hall, represents
the element Air. Along with Earth, Fire, and Water, Air was one of the
four elements ancient Greek scientists thought were the basic building
blocks of all things. The philosopher-scientist Empedocles (5th c. BCE),
who introduced the theory of the four elements into Greek thought, proved
that air was a body and not simply a vacuum by showing through experiment
that a container filled with air could keep water out.