Susan Hitchcock begins "Mad Mary Lamb" with what she calls "The Dreadful Scene Imagined": One Thursday afternoon in 1796, while preparing roast mutton and turnips, Mary Lamb killed her mother with a carving knife as she sat in her favorite chair.
She was in a trance, Hitchcock suggests. After years of selfless, grueling housework, the 31-year-old had slipped into delirium. The murder is her legend, and from the chronology of this biography, it seems to launch her life. In the aftermath of her gory crime, Mary became a pioneer of literature, a solace to her brother, a woman famous for her generosity and good sense.
Among the book's most startling aspects is the widespread compassion for Mary. Only five days after the murder, her brother Charles - a renowned essayist - wrote to Samuel Coleridge, "My poor dear dearest sister in a fit of insanity has been the death of her own mother."
Newspapers were equally sympathetic: "As her carriage towards her mother was ever affectionate in the extreme, it is believed, that to the increased attentiveness which her parent's infirmities called for by day and night, is to be attributed the present insanity of this ill fated young woman."
Legal concepts of insanity were nascent in 1796, but forgiving: The word "lunatic" had evolved from a notion of lucidity that waxed and waned. Between 1760 and 1843, nearly one in three acts of homicide, assault, or kidnapping was attributed to insanity. Murderers, it was thought, might be nothing more than instruments of Providence. With King George III's bouts of mental illness, interspersed with periods of competence, the stigma diminished further. Society grew increasingly comfortable with madness, and insanity ceased to be a blot on the soul.
To Charles, Mary's madness was nothing to avoid. He became a kindred spirit and careful guardian, making sure that Mary, in her time at madhouses, had fine and gentle care. Once his sister emerged, the two became housemates for life. Neither married, though both had close friends and held court in humble quarters with intellectual luminaries of the time.
It was a life of "double singleness," a relationship with all the fondness and reciprocity of marriage, but shorn of hierarchy, "a balancing act of mutual care and alternating excesses," writes Hitchcock. Mary and Charles "recogniz[ed] quietly between themselves that they both flirted with madness now and then."
Aside from Hitchcock's re-creation of the murder, told in italics with an odd, novelesque suspense, this is a calm and deliberate book. The lovely thing about Hitchcock's structure is that as the Lambs' lives continue, the crime recedes in the reader's memory, too.
After her initial, murderous episode, Mary was never dangerous. When she discerned a relapse beginning, she would tell Charles, who swiftly got her proper care. The episodes were rare at first - every other year or so - but became more frequent with age, and her depression ever deeper. Charles mourned his sister's absence and her misery, but he never complained of its burden. "'When she is not violent her rambling chat is better to me than the sense and sanity of this world," he wrote.
Mary was no iconoclast. Though she pushed the boundaries of women's roles and sanity, though she wrote books and befriended men as equals, she hovered in the shadows, apparently by choice. Seeing her confidence grow, from early, halting letters to eager collaboration on children's classics, is one of the book's great joys. Her work on "Tales from Shakespeare," with its unraveling of characters' switched identities, echoes her own contradictory selves: a sane and articulate woman who was capable of matricide, too.
Hitchcock's mesmerizing book is a story of madness witnessed and lamented, murder lived through and forgiven, and private mayhem that forged an extraordinary sibling bond.
• Christina McCarroll is an editor on the Monitor's national news desk.