If opportunity doesn't knock, build a door.
The wit here lies in rejecting the passive stance of waiting—but not through mere willpower or hustle rhetoric. Berle suggests something subtler: that we possess the actual materials to construct our own circumstances, rather than simply knocking louder or listening harder for distant footsteps. When a musician performs at open mics until a venue owner notices and offers a residency, she hasn't waited for opportunity; she's built the door by creating a pattern of visible competence. The quote's particular genius is that it doesn't ask you to become someone else or wish for luck—it assumes you already have the lumber in hand.