It’s neon.

Some old book has a monologue where a character says “I am neon” and the context is that they see themselves as beautiful and transient.

The subtext is that the neon gas in a neon light is just a medium power is passed through to produce some useful outcome through its interaction with the coating in the lamp (light). The neon itself is thrown away when it outlived its usefulness and no one who receives the light of it cares where it went or what happened to it or why.