The phrase deus ex machina is a Latin theatrical term meaning "god from a machine," although many sources translate machina as the crane used to lower actors to the stage. When the Romans conquered Greece, many of the Roman playwrights maintained the traditions of Greek theater, including the idea of using this technique as a legitimate plot device. Deus ex machina is the introduction of a contrived character, often a god or goddess, into a play in order to miraculously rescue the hero or resolve a complicated plotline. In many Greek and Roman plays, a god or goddess who had been watching the proceedings from a distance is suddenly lowered into the scene by means of a crane-driven cloud or chariot. Even if the introduction of the character makes little sense dramatically, the playwright could always be assured of an ending.
Over time, this plot device expanded to include any number of characters suddenly introduced for the sole purpose of resolving a complicated plotline. Even forces of nature might be used as a form of deus ex machina. The entire set may be destroyed by fire or a sudden earthquake, for instance. Audiences attending a Greek or Roman comedy were usually quite willing to suspend disbelief as long as the characters were entertaining. The Greek philosopher Aristotle, as well as other critics, often derided the practice as deceptive and unsophisticated.
In modern times, the plot device appears most often in soap operas or action/adventure motion pictures. Often, a complicated plot on a daytime soap opera is resolved by the sudden reappearance of a character assumed to be dead. Other plotlines may be resolved as the work of an evil twin or a character who has become criminally insane. One of the most controversial uses of it occurred on the television series Dallas. In order for actor Patrick Duffy to return to the cast, an entire season had to be explained as a nightmare suffered by his character's wife.
The concept of deus ex machina can also be applied to the business or social arena as well. Sometimes a hostile takeover is thwarted by the last-minute appearance of a new investor or financier, for example. Travelers stranded on the side of the road may be rescued by the driver of an empty bus. While the use of this type of ending in a play may seem artificial or contrived, their occurrence in real life often seems heroic or miraculous. A god or goddess may not arrive in a chariot in real life, but a tow truck driver or police officer often works just as well.