Morris, Christopher D. "The Direction of North by Northwest." Cinema Journal 36 (1997): 43-57.

    In this article Morris closely scrutinizes the title of the film "North by Northwest". As is noted elsewhere, this is not a true heading and many wonder where Hitchcock and Lehman came about the title. Morris sides with those who believe it is a play off of Shakespeare's line when Hamlet declares to his confidante Guildenstern: "I am but mad North-North-West. When the wind is southerly I know a hawk from a handsaw." From this, we understand that Hamlet has at least some (if not complete) control over his apparent madness. Perhaps he is strategically mad to his own ends, and the same could be said about Thornhill as well. Torn away from his posh lifestyle and Madison Avenue job, he is thrown into a world of foreign spies and front page headlines. For a good part of the film, nobody believes he is telling the truth and is instead attempting to deceive others about his drunken driving in a stolen Mercedes or rather that he has simply gone mad. Even his mother demands he "pay the two dollars", meaning accept the small punishment and end the charade. The audience is never completely convinced of the existence of a separate Kaplan until we find out Kaplan's wardrobe implies a man much shorter than Thornhill. In the end, Thornhill is vindicated and the truth would be revealed to all.

    Unlike Hamlet, Thornhill does not require long thought before actions. While Hamlet is often suffering in an existential quandary and must laboriously consider each of his actions, Thornhill acts impulsively. Until he falls for Eve he is in survival mode, looking only to clear his name and resume his comparatively dull life. It is through this apparent impulsivity that it becomes clear the madness is only a ruse. For example, his seemingly erratic actions at the art auction serve his interests of escaping the thugs. This shows Thornhill has great ingenuity and creativity at his disposal, no doubt skills honed from his career spinning slogans on Madison Avenue. The feigned madness that is shared between the Hamlet and Thornhill, coupled with the fact that North by Northwest is not a valid direction leads to the conclusion that the title is in fact a reference to Shakespeare's work.  By naming the film after this reference, Hitchcock helps the more insightful audience members better understand and analyze the actions of Thornhill and thus add the depth of the film.