“(Latin ‘god out of the machine’) In Greek drama a god was lowered out onto the stage by a mechane so that he could get the hero out of difficulties and untangle the plot. Euripides used it a good deal. Sophocles and Aeschylus avoided it. Bertolt Brecht parodied the abuse of the device at the end of his Threepenny Opera. Today this phrase is applied to any unanticipated intervener who resolves a difficult situation, in any literary genre.”
Excerpted from: Cuddon, J.A. The Penguin Dictionary of Literary Terms and Literary Theory. New York: Penguin, 1992