Deus ex machina

The phrase deus ex machina ['de.ʊs eks 'maːkʰi.naː] (literally "god out of a machine") describes an unexpected, artificial, or improbable character, device, or event introduced suddenly in a work of fiction or drama to resolve a situation or untangle a plot (e.g. the rope that binds the hero's hands is luckily chewed off by a rat, or an angel suddenly appearing to solve problems).

Origin

The Latin phrase "deus ex machina" has its origins in the conventions of a classical Greek drama. It refers to situations in which a mechane (crane) was used to lower an actor playing a god onto the stage. Though the phrase is accurately translated as "God from a machine," in literary criticism, it is more commonly translated to "God on a machine." It is a calque from the Greek ápo mēchanēs theós, (pronounced in Ancient Greek [a po' mɛ:kʰa'nɛ:s tʰe'os]). The first person known to have criticized the device was Aristotle in his Poetics, where he argues that a good tragedy must remain plausible.

Deus ex machina in Tolkien's Legendarium

Some events in the canon which could be considered to fall into this category are:

• The thrush that brings the message to Bard, enabling him to kill Smaug.
• The change of wind direction in The Return of the King, which turns the tides of battle in Gondor's favour.
• The appearance of Gwaihir and other Eagles who constantly save Gandalf whenever he is in a hopeless situation.
• Gollum's fall destroying the One Ring entirely by accident.