What Does the Expression “Flash in the Pan” Mean and Where Did the Phrase Originate?

On a pioneer flintlock rifle the hammer struck a flint to create a spark that ignited a small amount of priming powder in what was called the pan.

This ignition then set off the main charge of gunpowder, causing a small explosion that fired the bullet through the barrel.

When the powder in the pan didn’t ignite properly it created a flash, but the rifle wouldn’t fire.

It looked good, but it was only a “flash in the pan.”

Someone who doesn’t live up to expectations is called a “flash in the pan”.