Egri's premise is a complete proposition with a subject, an action, and a consequence: "great love defies even death," "blind trust leads to destruction." It is not a theme word ("love"), not a logline ("a detective hunts a killer"), and not a moral ("crime doesn't pay"). It's a specific claim about how life works — and every scene is evidence. A scene in a play about "ruthless ambition leads to self-destruction" must show ambition asserting itself, or the cost of that ambition accumulating, or the self-destruction advancing. Scenes that entertain without proving the premise are parasites — they feed on the audience's attention without contributing to the argument. The premise is the most ruthless quality test Egri offers: does this scene prove the premise? If not, cut it.
Check Your Script
State your premise as a complete proposition: [quality] leads to [consequence]. Now check your last three scenes — does each one prove some aspect of that proposition? Any scene that can't answer "yes" is a candidate for cutting.