An intertitle reads, “One upon a time…” We see a man (played by the director, Luis Buñuel) sharpening a knife. The film cuts between shots of the blade and the man’s face as he examines it while smoking. He steps onto a balcony, his shadow cast against the window. He looks up to the moon, as clouds approach it. The film cuts to a man (presumably the same man, though in this shot, unlike the others he wears a tie) opening a woman’s eyelid and approaching it with the razor. The clouds cut across the moon, in a motion similar to that of the blade’s cutting an eye. In the next shot, we indeed see the blade cut what we are meant to believe is the woman’s eye.
With its opening intertitle (“Once upon a time”), the film opens with expectations of a fairy-tale beginning, but it immediately upends those expectations. The first scene shows an eye being sliced open violently. We see a man, played by Buñuel himself, sharpening a razor. That Buñuel himself plays the author of this violent act may be a self-referential commentary on the director’s desire to shock his audience’s vision, as well as on the role of cutting (that is, editing, in the process known as montage) in a filmmaker’s process of conveying meaning to their audience.
This balcony will be one of the few visual tropes running throughout the entire film. We see Buñuel—this time wearing a tie and without a watch, unlike in the previous shots—hold open the eye of a compliant young woman. (Later, we will see this same woman sexually assaulted by a man. This scene thus initiates a concern with violence against her.) The film cuts to a shot of a thin cloud passing over the moon, a visual substitute for the act of cutting open the eye—a visual substitute suggesting that we will be spared having to witness the actual act. But nevertheless, disrupting this expectation, Buñuel cuts to a close-up of an eye being sliced open. (It is in reality the eye of animal—according to Buñuel’s own report, a calf—but it is edited and lit to suggest that it is the woman’s eye.) According to Buñuel, this entire sequence originated from a dream of his.
This scene initiates a concern with trauma, especially trauma to the human body, that will recur throughout the film. Other instances of trauma include not only the First Man’s sexually assaulting the Woman, but also the appearance of a hole in the First Man’s hand (with ants crawling out of it), and the appearance of a severed hand in the street. We might understand the scene of the eye’s being cut as an original trauma initiating the chain of traumas throughout the film. Or, relatedly, we might understand it as a trauma whose “memory” has been repressed and (just as repressed thoughts return in dreams and Freudian slips) returns in the form of the later traumas in the film. It is also a “memory” that appears to return in other forms: for example, the recurring image of a box whose diagonal stripes recall the downward motion of Buñuel’s blade.
The film scholar Elza Adamowicz has likened this scene to a sideshow magic act of the sort that Buñuel and Dalí would have seen as children (Adamowicz 78). Indeed, these scenes would typically feature a male magician performing a supposed act of trauma on a female subject (such as cutting off her legs), who then reappears unharmed. Thus, despite the fact that the following intertitle reads “Eight Years Later,” the Woman appears completely unharmed in the following scene. There is thus an extent to which the first intertitle, “Once Upon a Time,” is accurate in its suggestion of a fairy tale: the first scene initiates a series of magical transformations (including, later in the film, the Woman’s opening the door of her apartment onto a windy beach). The film underscores the importance of these magical transformations in the casualness with which it treats continuity errors: for example, in this first scene, Buñuel appears alternately wearing a tie and no watch, and wearing a watch and no tie.
A notable feature of silent cinema is the number of iconic images it produced of trauma to the human eye: not only in Un Chien Andalou, but also George Méliès’s A Trip to the Moon (1902), in which a rocket lands in the eye of the Man in the Moon, and in Eisenstein's Battleship Potemkin (1925), in which we see a woman’s eye being shot out in the Odessa Steps scene. The scene’s frank depiction of trauma to the human body also anticipates the “body horror” of such later filmmakers as David Cronenberg and Andrzej Żuławski.