“They will not let my play run; and yet they steal my thunder.”

Alternately reported as: "That is my thunder, by God; the villains will play my thunder, but not my play." Reported in Bartlett's Familiar Quotations, 10th ed. (1919).
Note: Dennis had written a tragedy, Appius and Virginia, for which he had invented a new technique for creating the sound of thunder, which the actors favored and which remained in use for centuries thereafter. The play itself was poorly received despite this innovation, and the management of the Drury Lane Theatre withdrew it. A few nights later, Dennis was in the pit at a performance of Macbeth, and heard his own thunder used; upon which he rose in a violent passion, and exclaimed with an oath, that it was his thunder. In Biographia Britannica, vol. v. p. 103. Conflicting reports exist as to whether Dennis actually used the phrase "steal my thunder", although it is undisputed that his experience is the origin of the idiom.
Context: See how the rascals use me! They will not let my play run; and yet they steal my thunder.