拉丁语词组Deus ex machina(英译:God from the machine)翻译自希腊语ἀπό μηχανῆς θεός(apò mēkhanḗs theós),意思是机关跑出的神,中文一般翻译为舞台机关送神、机械降神、机器神、解围之神……等。
这种手法通常被评论家认为是不高明的说书技巧,因为它破坏了故事的内在逻辑,纵使有时候会为了这个理由而故意采用。继亚里士多德之后,文艺复兴时期评论家将其视为一种迂拙的情节计策,虽然其仍然受用于文艺复兴时期的剧作家;莎士比亚将此计策用在《皆大欢喜》、《泰尔亲王佩力克尔斯》和《冬天的故事》。19世纪末,尼采批评欧里庇得斯透过这种计策将悲剧因素制造成乐观的类型,并促使他高度怀疑戏剧《blissful delight in life》是“希腊快乐”(Greek cheerfulness)。
尼采认为deus ex machina对苏格拉底文化恰好对症下药,重视文化知识过于酒神节的音乐并最终导致死亡的悲剧:
But the new non-Dionysiac spirit is most clearly apparent in theendingsof the new dramas. At the end of the old tragedies there was a sense of metaphysical conciliation without which it is impossible to imagine our taking delight in tragedy; perhaps the conciliatory tones from another world echo most purely inOedipus at Colonus. Now, once tragedy had lost the genius of music, tragedy in the strictest sense was dead: for where was that metaphysical consolation now to be found? Hence an earthly resolution for tragic dissonance was sought; the hero, having been adequately tormented by fate, won his well-earned reward in a stately marriage and tokens of divine honour. The hero had become a gladiator, granted freedom once he had been satisfactorily flayed and scarred. Metaphysical consolation had been ousted by thedeus ex machina.
尼采认为,deus ex machina制造出虚假的慰藉感觉,这是不应该寻求的现象,这种情节计策的诋毁普遍出现在评论意见中。一些20世纪的修正主义者的评论,建议deus ex machina不能在简化的用语中被查看,并主张此种计策是凡人“刺探”与神的关系。拉什瑞姆(Rush Rehm)特别引用希腊悲剧的例子,其中deus ex machina提供复杂化角色的生活和态度,当面临神的同时为观众带来戏剧的尾声。