The largest metaphor in The Serpent's Egg is the metaphor of the narrative film itself as a dream—the complete inversion of two levels of "reality." The film opens, for example, with a shot of people's expressionless faces, as they move in slow motion, like the figures in the boat in the dream at the end of The Shame; the shot is intercut with the opening credits. The film ends with explicit suddenness, accompanied by the metallic sound of a shutter gate dropping; the screen cuts sharply to black, and there are no closing credits. Throughout the film, there is also a vapor drifting up from the ground, whether it be the cold mist that rises perpetually from the cobblestones or the cigarette smoke which lingers in every cabaret and every bedroom. The narrator identifies this vapor as fear: "Fear," he says, "rises like vapor from the asphalt; it can be sensed like a pungent smell. Everyone bears it with him like a nerve poison—a slow-working poison that is felt only as a quicker or slower pulse or a spasm of nausea." Fear becomes the film's principal theme, the vaporous "slow-working poison" its principal image…. (p. 96)

The Serpent's Egg seems to wince occasionally on account of incipient politicalism, which is not, as his critics frequently remind us, Bergman's strongest intellectual suit. If Bergman means to say simply that we must think of the Nazi years as a "nightmare," Hitler a demon hatched from "the serpent's egg" to take upon himself the guilt and fears of the world in what T. S. Eliot has called the apocalyptic "years of l'entre deux guerres," then we would have to assume that his aestheticism and his tax troubles have gotten the better of his sense of history and his human sympathy. But it is far more accurate—and far more reasonable—to read Bergman's decision to situate The Serpent's Egg in Berlin during these years as a gesture of historical displacement, much like those he has made before, both in naturalistic films like The Seventh Seal and Smiles of a Summer Night and in expressionistic pieces like The Face and Cries and Whispers. Such displacement is a function and privilege of art, and not of politics and history, both of which must assume that the passage of events in time is real and can be analyzed as such; displacement deals not with the causal time-order of "real" events themselves, but rather with the way in which consciousness elaborates these events in its own forms of rhetoric. (pp. 97-8)

[Bergman has] constructed in The Serpent's Egg a film which revolves around a male protagonist. Abel Rosenberg eventually comes to live with his sister-in-law. Not unexpectedly, their relationship succumbs to a powerful sexual undertow which is, of course, neither technically "incestuous" nor immoral, since Abel's brother has already committed suicide; but it develops along intensely neurotic lines, nevertheless, and their inability to consummate it—that is, Abel's inability to consummate it, despite Manuela's growing desire to do so—is no doubt the thematic key to their dramatic personalities.

Actually, this character configuration is a variation on a theme which Bergman has played many times before: the woman has become both lover (or would-be lover) and mother-figure, the male both would-be lover and child-figure. Manuela feels compelled to take care of Abel as she had once taken care of his brother, and it is her guilt over her first failure which causes her to insist that they succor one another as if she and Abel, too, were lovers. "You're responsible for someone, and you fail in your duty," she confesses to a priest, "and there you stand, empty-handed and ashamed." Abel, too, suffers from a sense of guilt on account of his brother, but the paradoxical complexity of his guilt makes him a figure emblematic not simply of Abel, but of Cain as well: he is, it would seem, both the surviving brother whom not even death will release from guilt and, ironically, the victimized brother as well—emotionally murdered by the kind of guilt which is shared only by survivors and which can be relieved only by the kind of annihilation which he wills for himself at film's end. What all this guilt frustrates is ultimately sexual impulse and sexual self-knowledge, which is for Bergman … the most authentically human means of contact with the other and with oneself. (p. 99)

In The Serpent's Egg, Bergman has placed a male at the center of the film, and the issue of the male's sexual self-knowledge thus becomes the film's principal (if not over-riding) thematic issue. If the woman's special mode of self-knowledge is a privilege which derives from a sexuality culminating in the certitude of maternity, then the problem of the male's self-knowledge results from the complementary problem—the incontrovertible uncertainty of fatherhood….

The problem, of course, is not simply fatherhood itself, but rather fatherhood as the sign of the male's sexual equality—of his possession of his own sexual powers, of his equal participation in sexual experience, and of his equal access to self-knowledge. Bergman begins by following Strindberg in arguing that it is the irrefragable certitude of maternity which demands an acknowledgment of the woman's sexuality by the male which she need not reciprocate. In a film like Scenes from a Marriage, Bergman is concerned to describe the way in which an authentic sexual relationship can elicit the woman's acknowledgment, and it is Abel and Manuela's abject failure in consummating such a relationship which dictates the tragic end of The Serpent's Egg….

Abel finally wrenches himself free of Manuela's embrace and admits that he cannot be her lover, both because her maternal supplications have begun to suffocate him and, paradoxically, because he prefers the security which his child's role affords him. (pp. 100-01)

The film's key male figures, Abel Rosenberg and Hans Vergerus, represent opposite ends of any epistemological spectrum which is implied in The Serpent's Egg, and neither is able to approximate self-knowledge. Abel … prefers the kind of self-effacement for which the dream state is the primordial metaphor, while Vergerus prefers to watch the effects of self-extinction as they work on the object of his body. Except for the nightmares which he induces others to act out for him so that he may commit them to celluloid, Vergerus has no dreams of guilt and fear, and that is why he can purvey terror so confidently. For Vergerus, who looks into a mirror and watches the cyanide work on his own body, fear and death are necessary for the recovery of time and history: the scientist measures such phenomena as guilt and the fear of death according to the way they affect the body; then, by measuring the resulting "changes" in the organism, he assumes confidently the passage of time and the necessity of the future. The difference between Vergerus' clandestine scientific films and the filmed dream which is The Serpent's Egg itself is the difference, as Jorge Luis Borges is always telling us, between looking at oneself in the mirror and actually passing through the mirror itself. To pass through the mirror, as Bachelard puts it, is to create a world in which, as in the dream, the "real" world has been completely assimiliated into the "irreal" world of the imagination. When Bergman makes Abel Rosenberg's dream coextensive with the film which he himself has imagined, then he has assimilated the "real" world of his film—pre-Hitlerian Berlin in the 1920's—into the metaphor which he has created for it, and The Serpent's Egg, in the truest Borgian sense of the word, is thus a work of "fantasy." (p. 101)

Much like the art of Borges, Bergman's art is the transformation of reality into … "an inescapable reality of the mind"—a fantasizing of the nature of consciousness itself, experienced as one experiences a dream, as if it could not be distinguished from reality, and as if it were thus reality itself. (pp. 101-02)