The Moth Who Measured the Moon

A young moth claimed he could measure the Moon with one flight. He rose from a reed, flew until his wings tired, and returned before dawn. He announced that the Moon was four hundred wingbeats away. An old frog asked whether the Moon had seemed closer at the end. The moth admitted that it had not.

The next night, the frog placed two reeds a short distance apart. The moth flew between them while the frog counted. A breeze pushed him sideways, so the number changed on every trip. They waited for still air and measured again, but another problem remained: the moth’s wingbeats were not all the same length.

At last, the moth withdrew his grand answer. He had measured his own effort, not the distance to the Moon. Still, the frog did not mock him. The failed attempt had revealed three useful questions: Was the target reached, was the route steady, and was the unit constant? The moth wrote those questions on a broad leaf. Thereafter, he checked each unit against the same straight reed before measuring. He never measured the Moon, but he became the marsh’s most careful measurer of reachable things.