Ghost lights

Still today most theaters place a lamp on stage overnight as the only light in the theater.

Lots of theories on the purpose of the lamp. Some say it is truly for the safety of someone walking on stage in a dark theater. Nowadays I am sure it is easy to flip a switch or use a flashlight. Others say it is purely superstition to keep ghosts away.

One cool superstition I heard is it is lit to keep away the bad spirits of previous shows that failed in the theater.

Is there a real purpose?

The superstition I had heard was the light was to allow the the ghosts to play on the stage when the actors and other humans were gone. (Either as tribute or to keep them mollified so they won't interfere with the production, I'm not certain. Likely a bit of both)