"stole my thunder"
I had always assumed that this expression must have Greek mythological roots and perhaps was a reference to Zeus. The true story is much more prosaic.
John Dennis, an English poet and playwright, wrote a tragedy called Appius and Virginia, which was produced in 1709 to less than rousing commercial success. Only one element of the production stirred the audience: thunder sound effects more realistic than any heard before on the stage, effects that Dennis himself created.
The play failed, but the theater's next production didn't. Dennis went to check out a successful production of Macbeth and was more than a little upset to discover that his sound effects were used in the storm scenes of Shakespeare's tragedy.
Different sources vary slightly in describing what Dennis exclaimed upon hearing "his" thunder help promote the new production, but they are all variations of Stuart Berg Flexner's quote: "See how the rascals use me! They will not let my play run, and yet they steal my thunder!" I'm sure that Dennis would be even more embittered to learn that the only phrase of his that has gained immortality is his expression of sour grapes.
54 minutes ago