Lightning image, which is kind of related to thunder, via Shutterstock
While we use the term figuratively today, its original usage — by English playwright John Dennis in the early 1700s — was literal.
Live theater productions have plenty of sound effect tricks up their sleeves, some of them centuries old. If the sound of thunder is needed for a stormy scene, for example, off-stage crew members might roll metal balls down troughs, grind lead shot in bowls or shake thin sheets of metal.
For the performance of his play Appius and Virginia at a London theater, Dennis came up with a new thunder effect, a refined version of the “mustard bowl” that used metal balls in a bowl instead of lead. The play was not well received, but the thunder was, and after Appius and Virginia was cancelled, the theater manager continued to use Dennis’ thunder-making method for a production of Macbeth.
One night, Dennis was in the audience and recognized the distinct sound of his thunder effect. According to legend, he leapt from his seat and shouted, "That's my thunder, by God! The villains will not play my play but they steal my thunder."