Mad Men and Medusas: Reclaiming Hysteria and the Effects of Sibling Relations on the Human Condition
Juliet Mitchell
Allen Lane, £20, 380pp
Buy it at BOL

Svengali's Web: The Alien Encounter in Modern Culture
Daniel Pick
Yale, £19.95, 284pp
Buy it at BOL

Here come two books to remind us that nothing much has changed in the old unconscious: we just call things by different names. Instead of worshipping gods and fetishes we have genetics and the internet - but strip away all the fancy wrappings, and we're back to life and death and the unknown.

Juliet Mitchell is a prolific writer, psychoanalyst and feminist whose new book sets out to "reclaim" hysteria, a subject she feels has been relegated to the 19th-century consulting room. Before Freud, hysteria went through various mutations. In 5th-century Athens it was named usterie and diagnosed as being due to a wandering womb, although both men and women were thought to be susceptible to it. Christianity turned it into the work of the devil and the Renaissance recognised it as a medical concept. But it was Freud, in analysing Dora, who finally rid hysteria of its mysticism and - Mitchell argues - feminised it.

In the 20th century, psychiatrists have redefined hysteria in various ways. Histrionic personality disorder replaces hysteria as an entry in the Diagnostic Statistical Manual.

Mitchell believes that Freud brought about the feminisation of hysteria to avoid his own unconscious conflicts about the death of his brother. One of the new concepts she introduces is that, contrary to traditional psychoanalytical theory, it is sibling rivalry as much as Oedipal conflict that underlies hysteria.

Mitchell relates this to a concept called "laterality", meaning relationships not only with brothers and sisters, but with peers and partners - with anyone who might stand between ourselves and our mothers, rendering us helpless. She writes: "It is this catastrophic awareness that one is not unique which triggers the onset of hysteria." Freud, she argues, was himself a hysteric, but unable to face it, hence his suggestion that hysteria was a female disorder. The idea has since been perpetuated by a largely male medical and psychiatric profession.

Because we've done away with carnivals and symbolic rituals as a way of expressing our hysteria, we have had to find other means. In some cases, hysteria is turned in on the body; what was known as conversion hysteria in Freud's time - paralysed limbs and the like - has become psychosomatic illness. And because a major feature of hysteria is mimicry (the hysteric is even capable of imitating his or her own illness), it is very difficult to pin down.

Mitchell quite convincingly argues that hysteria is closely linked with trauma, although it is hard to know which comes first: does trauma result in hysteria, or does hysteria lead, for instance, to the recalling of an incident, as in false memory syndrome? In either case, for a man, hysteria as a result of trauma will probably be called "post-war neurosis" or even schizophrenia, while for a woman the hysteric label remains, with an implication of play-acting, deliberate or otherwise.

The fairly dense jargon in Mitchell's book - its repetition and wordiness - don't make it an easy read. Nevertheless, she has some interesting things to say about our hysterical culture and the fascinating strangeness of human behaviour.

Less of a slog, but with just as many important things to say, is Daniel Pick's Svengali. He uses George du Maurier's story Trilby as his springboard into an exploration of the Victorian psyche. Du Maurier's tale is a deceptively simple one: Svengali, an intinerant conductor of "Jewish aspect, well featured but sinister", hypnotises a young artist's model, Trilby, without her consent. She eventually marries him and becomes an international concert star, but sings only when under his spell.

The book, published in 1894, gripped readers on both sides of the Atlantic. Was Svengali purely a creation of Du Maurier's imagination, or was he a product of the age? Pick sets out to show how our unconscious needs dictate who we make into our Svengalis. Fast-paced and gripping, using as examples a broad range of people including Disraeli, Wagner and even Jenny Lind, the book shows how the figure of Svengali reflects a need to project onto the alien Other - often the foreigner - unwanted and dangerous unconscious desires. The Other then possesses the power that we have handed over, and in turn becomes both fascinating and terrifying (Pick pays tribute to Melanie Klein for her conceptualisation of projective identification).

The Victorian love of fluff and nonsense, of smoke and mirrors, covered myriad anxieties. There was an obsession with, and terror of, the unleashing of emotion, particularly sexual. The story of the innocent Trilby and her Svengali is rife with sexual implications that were picked up by an excited and anxious public.

Du Maurier received letters demanding reassurance that the relationship was merely paternal. After all, "If a prostitute could be made to renounce her trade through hypnotic interference, why might not a virtuous woman be perverted by the same method?" The Victorians were full of contradictions: fascinated by science, they were equally drawn to mesmerism and the occult. And while hypnosis was being performed on stage as entertainment, it was also being used in the consulting room by Dr Freud - upon susceptible young women not unlike Trilby.

The terror of being seen into, of being controlled, is as powerful today as it has ever been, so perhaps it is inevitable that psychoanalysis should be linked with the Svengali-like figure of the hypnotist, who can take control of the very soul. Call it what you will, the shaman or witch doctor (pop star? guru? spin doctor?) who has the potential to cure or to con has always been with us.

Pick's book exerts its own power over the reader. It can be read as a well-researched, entertaining story of the Victorian age, or as a serious and important contribution to an understanding of the human psyche. He exposes our longing to be overpowered by our very own unconscious forces, as well as our dread of being overwhelmed. We battle not with the Other, but with ourselves.

• Victoria Davenport is a psychotherapist.